Lots of hostility here! I don't go to shows much lately as I was always there to buy if I found something interesting, and right now NYU Film School for my daughter takes precedence.
However, gun shows have always been a good place for me to find good prices on soft gun cases, gun books, bulk ammo, old reloading equipment, and interesting odd stuff. I once picked up a Line Throwing Gun that weighed about 150 lbs. I use it to shoot concrete-filled Schaefer beer cans out over the river. Paid $230 for it IIRC.
The dealers at local shows know me, know what I like, and know I carry cash. They'll draw my attention to things like older N-frames, usually offering them at what I feel is a fair price, and sometimes I buy.
Since I never come in with stuff to sell, I have no experience with people trying to rip me off with ridiculous lowball offers, but if that happened, I'd just laugh and say "I'm looking to sell this gun to someone that wants to OWN it, not flip it for a profit."