How to find things to read
You need to think about how you can access reading.
Depending on your context (access to libraries and the like) you might be able to do all three Modules without buying any books, but you have made the decision to invest in your long term professional development and buying (the right) books is a further useful investment.
Books
The modules we run at ITI are based in Istanbul, but we have candidates working on line all over the world as well as those who come here to do face to face elemens of courses. Some of this advice will work for people in cities big enough to have a university (or two) in them and some of it will work with just an internet connection.
A lot of the kind of thing you need is available second hand (via Amazon on the 'buy used or new' button, or via specialist sites such as Abebooks). The postage often makes these expensive if you are in more far flung places, but if you know someone who is coming from the UK or the US within the time frame you need, they are a great option. This means planning ahead though as books often take weeks and weeks to arrive.
If you are in a city, is there a British Council and does it have a library ? If so, that may meet a lot of your needs (the one in Istanbul used to be great, but sadly is gone now). If there is no British Council library, are there universities ? Did you go to one of them ? If so, you will probably find you can use the library. If you didn't, do you know anyone who did ? Can they be persuaded to take you on occasional library expeditions ? Also in the same vein, do you know anyone who has done Delta or a related Masters in the last few years ? They may be happy to lend you what you need. If a group of you are doing Delta together (it can be nice to have the moral support), share out the load. Buy one or two things each and pool them.
More and more books are becoming available electronically, so if you use a reader it is worth looking at that option. CUP have started putting a lot into Kindle format, Macmillan offer a couple of things (the most useful of which is Underhill Sound Foundations) through their own web site in adobe digital or other formats, some publishers seem to be operating through ebooks.com if you use an epub reader. This seems to be incresaing rapidly, but it is harder to track down than you would expect and there are geographical restrictions (some of which you can work round by having your address registered as in an appropriate country, but other sites check ISPs and restrict sales and downloads). Some books are sensibly priced and some even slightly lower priced in eformat, but others are much more expensive so check carefully.
Journals
Think about subscribing to magazines and journals in the longer term (after all, your next step might be to think about writing pieces for some of them). By the time you have finished your DELTA you will have worked out which ones you prefer.
English Teaching Professional is accessible and if there are back copies in your school it often has articles that can be cited as reading. Subscription gives you access to some of the back catalogue.
Modern English Teacher is similar.
English Language Teaching Journal ELTJ is more academic - perhaps the most accessible of the more academic journals. It can help with Module One, but really comes into its own in Module Two background assignments and can also help out with some of the reading for Module Three. Again a lot of this is because you can access back copies on line with an on line subsription.
There are a lot more, but these three are probably the most directly useful.
There are some free journals on line (the most well-known of which are TESL-EJ and the IH Journal).
You can often access elements of things if you search around
e.g. some back copies of the Language Teacher
or some of the key concepts articles in ELTJ
Some absolutely wonderful writers link to some or even all of their journal output on their web sites. Whether they should or not is a hotly debated issue, but if you are studying (especially for Modules Two and Three), a wonderful thing. Examples are Scott Thornbury, Paul Nation and Ken Hyland, so if you find a name comes up regularly in the area you are interested in reading about, try tracking down their web site.
Web sites
There are lots of sites which publish information for teachers and it varies in quality enormously. Try places like the British Council and Onestopenglish. You can find much more yourself, but bear in mind that not everything that is on the net (or even in these sites) is correct or useful.
Blogs can be great for ideas for Module One (language analysis, phonology, hotly debated topics) and if you find blogs of authors who are pulished in an area you are trying to read up on, they may also be useful for Modules Two and Three.
Desperation
It is better to read things in context, in the book or in the article it was mean to be in, but sometimes you can't.
You can get a lot from Google books . Some books have previews and some of those previews let you read several different chapters (a good way of deciding if you might want to buy something).
Another similar alternative is the sample chapters that are often provided by publishers. For example on the elt.oup.com site look in the catalogue, go to applied linguistics, click on the name of a book you like the look of and you can read the first 10 or so pages, sometimes the whole of the first chapter (and it usually allows you to see the contents page so you get a clearer idea of whether it will actually be the kind of book you want or not).
Depending on your context (access to libraries and the like) you might be able to do all three Modules without buying any books, but you have made the decision to invest in your long term professional development and buying (the right) books is a further useful investment.
Books
The modules we run at ITI are based in Istanbul, but we have candidates working on line all over the world as well as those who come here to do face to face elemens of courses. Some of this advice will work for people in cities big enough to have a university (or two) in them and some of it will work with just an internet connection.
A lot of the kind of thing you need is available second hand (via Amazon on the 'buy used or new' button, or via specialist sites such as Abebooks). The postage often makes these expensive if you are in more far flung places, but if you know someone who is coming from the UK or the US within the time frame you need, they are a great option. This means planning ahead though as books often take weeks and weeks to arrive.
If you are in a city, is there a British Council and does it have a library ? If so, that may meet a lot of your needs (the one in Istanbul used to be great, but sadly is gone now). If there is no British Council library, are there universities ? Did you go to one of them ? If so, you will probably find you can use the library. If you didn't, do you know anyone who did ? Can they be persuaded to take you on occasional library expeditions ? Also in the same vein, do you know anyone who has done Delta or a related Masters in the last few years ? They may be happy to lend you what you need. If a group of you are doing Delta together (it can be nice to have the moral support), share out the load. Buy one or two things each and pool them.
More and more books are becoming available electronically, so if you use a reader it is worth looking at that option. CUP have started putting a lot into Kindle format, Macmillan offer a couple of things (the most useful of which is Underhill Sound Foundations) through their own web site in adobe digital or other formats, some publishers seem to be operating through ebooks.com if you use an epub reader. This seems to be incresaing rapidly, but it is harder to track down than you would expect and there are geographical restrictions (some of which you can work round by having your address registered as in an appropriate country, but other sites check ISPs and restrict sales and downloads). Some books are sensibly priced and some even slightly lower priced in eformat, but others are much more expensive so check carefully.
Journals
Think about subscribing to magazines and journals in the longer term (after all, your next step might be to think about writing pieces for some of them). By the time you have finished your DELTA you will have worked out which ones you prefer.
English Teaching Professional is accessible and if there are back copies in your school it often has articles that can be cited as reading. Subscription gives you access to some of the back catalogue.
Modern English Teacher is similar.
English Language Teaching Journal ELTJ is more academic - perhaps the most accessible of the more academic journals. It can help with Module One, but really comes into its own in Module Two background assignments and can also help out with some of the reading for Module Three. Again a lot of this is because you can access back copies on line with an on line subsription.
There are a lot more, but these three are probably the most directly useful.
There are some free journals on line (the most well-known of which are TESL-EJ and the IH Journal).
You can often access elements of things if you search around
e.g. some back copies of the Language Teacher
or some of the key concepts articles in ELTJ
Some absolutely wonderful writers link to some or even all of their journal output on their web sites. Whether they should or not is a hotly debated issue, but if you are studying (especially for Modules Two and Three), a wonderful thing. Examples are Scott Thornbury, Paul Nation and Ken Hyland, so if you find a name comes up regularly in the area you are interested in reading about, try tracking down their web site.
Web sites
There are lots of sites which publish information for teachers and it varies in quality enormously. Try places like the British Council and Onestopenglish. You can find much more yourself, but bear in mind that not everything that is on the net (or even in these sites) is correct or useful.
Blogs can be great for ideas for Module One (language analysis, phonology, hotly debated topics) and if you find blogs of authors who are pulished in an area you are trying to read up on, they may also be useful for Modules Two and Three.
Desperation
It is better to read things in context, in the book or in the article it was mean to be in, but sometimes you can't.
You can get a lot from Google books . Some books have previews and some of those previews let you read several different chapters (a good way of deciding if you might want to buy something).
Another similar alternative is the sample chapters that are often provided by publishers. For example on the elt.oup.com site look in the catalogue, go to applied linguistics, click on the name of a book you like the look of and you can read the first 10 or so pages, sometimes the whole of the first chapter (and it usually allows you to see the contents page so you get a clearer idea of whether it will actually be the kind of book you want or not).