Powells.com is offering a credit for used books. You submit your ISBN for any book that is in “good condition” meaning that there should be no pages torn, no writing in the books, original dust jackets, etc. The computer then checks the ISBN and either makes an offer or declines.
If Powells makes you an offer and you agree, Powells will pay for the shipping (in the US). You must ship within 1 week for the offer to be valid. Once the books are reaceived, you’ll get a credit against other purchases.
I buy ebooks from Powells. I may have to start using this service.
Via Shelf Awareness.