Better World has their own website, but also sells on all the major books sources--Amazon, Abebooks, Alibris...
I go out of my way to look for books distributed by Better World. Why? Two reasons:
1) GREAT service. I like a company that puts a personal touch on the process, one that keeps me informed, one that works fast to get my product to me. I've always gotten exactly what I expect in both quality and content.
2) I'm doing some good in the world while filling my shelves with the books I want. From their website:
"Better World Books is a for-profit social enterprise that collects used books and sells them online to raise money for literacy initiatives worldwide. We offer great bargains on used books - over 6 million used and new titles, with free shipping anywhere in the U.S. and just $3.97 worldwide. What’s more, you love cheap used books and so does the environment – when you buy used, you save books from landfill and conserve resources."
What more could you ask for?
BETTER WORLD BOOKS