Save Time & Save Money On Textbooks

Recently I've decided to study GRE and Mathematical Finance. I've got a list of good books on these subjects, but they would cost a fortune if I buy them. So here is what I did:

1. Check with the local library. I was agog to discover that my local library carries all the GRE related books on my list. There are two good reasons of using borrowed books to study the GRE: (a) these books are valuable only temporarily and will be worthless after I took the test; (b) a return date will help stop me from procrastinating.
2. Use ILLIAD. ILLIAD is a system that allows you to borrow books from all participating libraries nation wide. Since lots of university libraries are participating, it is a good way to borrow textbooks. The only disadvantage is that the book loan length is usually 3 weeks, and sometimes the whole borrowing process can take a month before the book is delivered to your hand. But hey, it is free textbook. I used this service to borrow some of the mathematical finance books on my list, and of course, 3 weeks is not enough for me to go through the book thoroughly, but it will tell me whether it is worth to buy it. Once I decide it worths the money to buy, I then go to the following website.
3. http://bigwords.com/ What this website does is to compare all the offering prices of the book you are interested in listed on all the online book stores and give you the best one. Moreover, if you are buying a bundle of books, then it can compare all the prices of them at the same time and give you the store combination that will cost you the least. Then you can purchase them individually through each particular store. This saves huge time and big money. I've got two books via this website.
4. Free Downloads: http://read.freeduan.com/ This website provides tons of links for free download for technical books such as math, engineering, programming, etc and popular magazines. Registration is free (you only need to provide an email) and required to see the download link. I strongly suggest to check this site before you buy any books.