I used to sell a fair amount of books here, most being children's. I loved what jewelerydesigns said as well as bittersweetpunkin. I want to add that adults have often purchased a book that they lost as a child, or to give to a grown friend on a birthday for what ever reason. Also, I think many of my books were valued by buyers becuase of the 'artfullness' of the illustrations. I loved selling them, but found the task of scanning and writing up the description very lengthy for the value. Still, I have 100s to list, and hope I can get some more up after the holiday.
Best of luck!