Start haunting your local thrift store or goodwill. I've found unbelievable amounts of books in good to great/like new condition for about 25 cents each. These way you can have books that the baby can "read" herself and don't worry about them getting torn up.
Also, check out the Kohl's Cares for Kids books. They come out with a different set each quarter. The books revolve around a theme. They are usually hard back books. Normally (but not always) there are four books and four matching stuffed animals. Right now they've got the Clifford books. In the past I've gotten the Eric Carl books, Curious George books, and the Duck Soup books. I've also seen the Dr. Seuss books there too. Books and stuffed animals cost $5.00 each.