I bought Resident Evil and Resident Evil Zero for $15 each, and although I plan to swap the cases with new ones eventually (used DVD type cases are ugly and scratched up looking in the clear cover part), I thought the discs were in mint until I got them home and examined them quite a bit more. There are some tiny scratches on them that I didn't notice when examining them in the store (must have been the lighting). One has quite a few in a small spot, but you can only see them if you hold it at a certain angle. How does the Gamecube handle scratches?
Either way, I regret buying both, when for only $5 more (each) I could have probably purchased both new (albeit 'PC' titles). But since they are 'PC' titles, the value is obviously low and should have waited. Hindsight is always 20/20.