You gotta look, Blue. When I go to a gun show, I fully expect to look at 500 guns before I make an offer on one and I only buy one in four or five of those that are worth dickering over. But while I'm there, I stock up on primers, catch up with some old friends, tease the sharpies with what I have to sell, maybe find a mould or clip that I have been looking for, and generally have a good time.
There are still bargains to be had, but you gotta know your odd stuff to get them. If everybody knows what something is, they are pretty likely to have a good idea what it sells for. The exception is that milsurp comes in waves. Stuff that has just been imported in bulk often sells for half of what the item sold for last year and one third of what it will sell for in five years when the supply has dried up.