The uniformed officers at the gun shows are paid for by the promoter for security. The NICS bacground check is free for licensed dealers. In California you used to have to involve a dealer for a transfer. The dealer would receive it in to his books, then transfer it to the buyer. But in Kalifornia there is a fifteen day waiting period on all purchases. I suspect one of the Laws that will be pushed by the "left" will be mandatory checks on all purchases at gun shows. I personally would hate to see it, but there would be an opportunity for a dealer to make $10 or so for a few minutes work and a phone call.
This ... And if I had to pick a knife to stick myself with, I'd rather it be this than some of the other stuff I've heard floating around out there ...