Going by the last GB they were $8/8.50 ea, I'm not looking at paying new prices if they are used.
$5/6 ea seems reasonable.
OP, most people put these keys in a position that hardly or never gets pressed. Mine are on the print/ScrollLock/pause key, which NEVER gets pressed. So it's not really "used", and I'm assuming most people do not buy novelty keys to constantly mash the hell out of them until they shine.
Second, $5 is not reasonable. If the leftovers are being sold at $8 or over, just after the GB ended, then expect to pay a lot more than that if you're just asking for them at this time. Prices will be higher the longer you wait, not lower. I was going to offer until I saw what kind of prices were you expecting to buy it.
People buy Clack keys for $13 brand new, and yet they're being sold for more than $50. Try finding someone selling them for less than $13. This is the same idea. Not trying to threadcrap, but just giving you what a realistic expectation is. Good luck finding a seller.