Who knew there was another way to buy really cheap books online besides used booksellers on Amazon? Behold...Thrift Books.
Here's the 411 from their site:
Thrift Books was founded and created on the principle of offering the public the lowest priced items anywhere on the internet. While many companies claim they have the best prices, Thrift Books guarantees the best prices!
Thriftbooks.com guarantees the best prices on everything we sell. If you find a lower priced-item* (item price + shipping) on another website, Thrift Books will match that price and refund you 10% of the total purchase price. So whether you buy 1 item or 50 items – we promise you will not find a lower price anywhere else on the web.
I haven't had a chance to buy a book yet, but a few examples on the home page are intriguing.
Eckhart Tolle's New Earth $1.20
Philippa Gregory's The Other Boleyn Girl $0.01 (!)
Rachael Ray 365 Cookbook $0.01(!)
Found here, which is why I love the internet.