Once again, I cannot say enough nice things about Noble Knight Games. They've made my most recent selling transactions a breeze. Aaron at Noble Knight is very helpful and knowledgeable, and even covered the shipping on the books I sent in (which was a very good thing). I ended up getting a bit of store credit, which was very easy to use in their store. In an industry where delays and lags seem to be far too frequent, Noble Knight stands out as a customer-friendly business.
I definitely can recommend Noble Knight for any game selling or older/out-of-print RPG purchasing (as well as newer titles for that matter) you're looking to do.