I have not purchased books from OU. I have rented/bought from Chegg.com I just went on there today to sell back a book. It's really easy. Just find the link for selling books and it will prompt you for the ISBN then give you a quote. Be sure to print the quote to put in with the book. It's a very easy site to work with and I've had nothing but good luck with their customer service...second to none. I plan to use them on into grad school.