any good online places? Besides Ebay, half.com and barnes & noble? Thanks

I have a few textbooks that are mostly out of print, and I know that all of the buyback sites online do not take out-of-print or non-current edition books. What can I do? Should I try eBay?

My school runs as a quarter system, and I do not know when is the break for semester system campus.
I want to sell used textbooks at a right price at the right time on eBay.
Any ideas or experience you guys have?

Thank you so much!