Website: www.alibris.com 

Alibris specializes in selling new, used, and out-of-print titles through the assistance of third-party vendors. The site has one of the most unique and easy-to-use search engines, as well as the best customer service found on any online textbook retailer. A number of payment options can be used to purchase books, including all major credit cards, Google Checkout, and Paypal. Shipping options include standard, overnight, and expedited, plus discounts are given to buyers who purchase more than one item from the same seller. And like Chegg, it promotes a 60-day money-back guarantee policy. Once the semester is complete, you can sell back your textbooks directly to the site, which then compensates you via check or PayPal, or put it up for sale on the marketplace.