eBay. You can check Abebooks for the price the dealers are asking, but then you can check eBay for the true value. Click their site map tab at the top of the page and on the next page go about halfway down to Completed Listings on the left. I think they hold the completed postings for 2 weeks. (You need to be a member with a password to look at the Completed Listings). Makes me shake my head when I see what some of those books just sold for. I expect to get about a quarter to a half of the top price Abebooks lists, and I fix a reserve at that quarter to half. If I got the book cheaply, why not take a decent markup and move on? Good luck.