Check with the organizers of the gun show to see if they have any rules or expectations on how you conduct yourself if you are a casual seller.
I don't go to a lot of gun shows any more because the sellers at the shows (at least from my past experience in the Dallas area) seem to be asking astronomical prices and don't really seem all that interested in negotiating. Of course, that could be good for you if you are a seller with something appealing.
I was at a show in Pine Bluff, Arkansas, and while I couldn't buy any guns (Texas resident at the time), the sellers were willing to vigorously negotiate on the accessories, parts and components I wanted. The surprising thing was they were some of the same sellers that had been in Dallas only months before. I guess the fact Dallas is wealthy and Pine Bluff is impoverished had an effect on their viewpoint.