I also recommendt www.half.com I highly recommend half.com. I purchase movies, books and cd's from them and I have saved tons of money through their website. They are used items but in very good condition; most like new.
For non-muslims. If you truly wish to understand the religion of Islam you should try and use the islamicbookstore.com for resources. Many of the books at that site are not found at amazon.com or other bookstores. If you were wanting to know more about the catholic religion you would not ask a baptist about it; right?? So why do non-muslims insist of finding out about the Islamic religion from non-muslims. Use your common sense. There are tons of books available out there that will give you the truth about the religion.
If you are converting to Islam some words of caution. When I first started to convert I was confused by some people who were saying that I should be doing this and that and certain things were haram and others would say no that is not true. READ!! LEARN!! and DISCOVER!! SEEK the knowledge and you shall find it. There was a lot of sorting out I had to do among cultural differences; etc. Make sure you use good resources to get the correct information.
Books
Complete Idiot's Guide to Understanding Islam ***** Yahiya Emerick (excellent read)