I save a lot of money by using the library for quilt books. I've found that as much as I like to look at quilt books, I don't actually make that many quilts directly from them, I just use them as a reference for techniques, or block designs. So checking out a book is as useful to me as buying one, most of the time, and much cheaper.
I also use Bookmooch to get books. A lot of the quilting/craft books available aren't current, but the great thing about quilting is that the classics never go out of style. I got two Georgia Bonesteel books that way, and I've used them a lot.