I meant the used book store case. I have a hard time thinking of used books with high resale value that the needy need. Maybe they exist. Valuable used books are generally out of print due to low sales. Or they're specialty books that weren't ever printed/read in large numbers. I'm happy that I got some expensive-on-Amazon old books from the free giveaway shelf of a technical library, but I don't think the needy are often looking for Opioid Analgesics: Chemistry and Receptors in the first place.