I understand! You are a student/creative type/zombie (delete whichever is inappropriate), and as such you have no money. But you love books, and you long to collect them all. How can you support your favourite authors when you lack cash to buy books?
1. Go to the library. If you are not already convinced of the utter magic of libraries, we need to have a chat.
My local library network is the most amazing thing ever, because if they don't have a book I want at the nearest library they can order it in from another library. It mysteriously appears on the holds shelf a few days later. Marvellous stuff. Saves me a lot of bus travel. Plus, plus, I can place holds online (they limit it to ten which is sad because I get so excited about placing holds, I want to place fifty at once) and they have this whole e-book lending thing. Being that I don't have an ebook reader, I don't borrow many of these, but it is also awesome. Instant access to as many books as your heart desires! (Or that the system will let you have out at once. Also capped, probably due to people like me.)
There is a quite wonderful thing we have in Australia called Educational Lending Rights and Public Lending Rights, wherein authors are reimbursed some of the income they've lost from their books being available in libraries. You know downloading books illegally is super dodgy, so don't do that. Borrow from the library instead.
Also, libraries have air-conditioning and computers and nice places to sit (the children's fiction area is the best but frequently has children in it who are renowned as the noisest of humans, followed by drunk people. Maybe you local library has a good YA spot too). I am not even mentioning school libraries here. I am insanely jealous every time I visit a school with an awesome library. If your school library doesn't have a book you want to read, ask them to order it in!
My next book is just a 500-page ode to the library. It's my Narnia, with significantly less evil witches.
2. Talk about the books you love. This was why I started my blog! Of course, you don't have to be talking about books on the internet - you can just recommend books to friends and family. I was trying to avoid driving everyone I knew insane by talking incessantly about fictional characters. Other people with the same reading tastes as you might read your review and decide to pick up that book. So, you know, your favourite writer finds another reader, another reader finds a new favourite writer, everybody wins.
3. Buy books as gifts. I mean, if you're going to be buying someone a present anyway, why not make a book? Give the gift of reading, you guys. It's the best gift ever. Along with baked goods. If you give a book as a gift to someone you live with, then you can just borrow it from them and forget to return it at a later point. Personally signed books are also a really special gift that aren't necessarily any more expensive. Save up your Christmas fund, go to a writers festival and stock up. Be super nice AND save time by buying books by the authors that don't have enormous queues at the signing tables.
4. Write to your favourite authors. Fan mail is the greatest thing ever and is really encouraging (this is what I think, at least). If you want your favourite writer to keep on writing, let 'em know!