Well, shoot, if it's only $400-$1500 for a booth you might actually find enough interest to make it worth while. Mike Caldwell or MemoryDealers should honestly go and set up a booth and sell coins, I'm pretty sure they could recoop the costs of a booth pretty easily. A greater concern might be security at an event like that. You could probably sell a few thousand BTC in one weekend though. Especially physical coin. There were at least a few thousand in attendance at the 2008 convention, and every single one of them would be interested in a decentralized currency for sure. Most of them will have probably heard of it, too, so you could just put up a sign saying "Physical Bitcoins Sold Here" and they'd sell themselves.

Actually, just thinking about this is making me want to buy Bitcoin ahead of time since Caldwell or MemoryDealers would eventually have to restock.