There are four websites that you might want to look at. Try "www.bookbyte.com", "www.abebooks.com", and "www.ecampus.com". My GD buys the books for her husband who is now in his Masters Program. The bookbyte website has had the cheapest and best prices for her. But she found that all three were less than Amazon or e-Bay. There's also "www.chegg.com" where you can rent the books which come with a return label when you receive them. Hope this helps.