Found: One very battered copy of Psychonauts for the PC, buried among a pile of similarly unwanted PC games (which were not all horrible. there were games in there I'd heard of. Just nothing that was really popular - and the adventure games present were Not My Type) in a discount store. Not quite a dollar store, but definitely a 'random junk' store. It needed rescuing.
Also found: One copy of Magical Starsign for the DS, used, at a game store. DS games seem to hold their value a lot more than most videogames do. The used prices are barely distinguishable from the new prices. Perhaps because since the DS isn't bleeding edge anyway, the customers are less eager to dispose of last month's games in favor of the latest shiny? Anyway, we went there hoping to find a copy of Mario Kart cheap (as I have one, but two would enable us to share more races) but even in a generic store box, no manual, the price was still very high. MOST used games were pretty pricy, saving only Sprung, the western Dating Sim that generally nobody liked, to the point that I could only remember negative reviews and couldn't figure out whether it was worth even a few bucks for research purposes.
Anyway, Magical Starsign was the best intersection of quality and cheap that I could find.