$500 is nothing compared to having your butt hauled to jail for breaking copyright. Odds are that the company who is organising the show will have a clause about that.
You can bump all week long, but I would be surprised to see anyone sticking their necks out for the trouble.
And your trouble too while we discussing it.

Call these guys, they might rent you a machine for your booth:
Mountain Coin Machine Dist.
5675 S. Valley View
Las Vegas, NV 89118
Telephone: (702) 798-0900
Fax: (702) 798-8431
Tell them I sent ya.
$500 sounds right for a day or two.