don't know if anyone has heard of this site...
you can join for free... if you post 9 books, you get 3 credits free. Any book you order is 1 credit. When someone requests one of your books, you mail it to them media mail. When they receive it, you receive 1 credit. It started out as paperbacks, but there are quite a few hardbacks on there.
if you decide to join... refer to me "KathyJ" and I'll get a credit for the referral.