My local Gamestop, which doesn't even have a Gamecube Kiosk, has two copies of every Gamecube Interactive Demo made, sealed no less, but can't give them too me. Or sell them. In fact, they give me pretty much any store display I ask for, just not those, because they say "Not for resale" on them. D'oh!
Again, I'm looking for those, so if anyone has them, I'm willing to dive into my not-for-trade collection to aquire them.