Best advice I can give is to start in one corner of the building and snake your way through so you see everything.
You'll get an idea of who has what and who is price gouging this way.
For pistols, I usually gage price off of zx. They have pretty good prices that are normally not TOO far off Internet prices. If someone wants less that zx, it's normally a good deal. If they want more, haggle them down. Let them know the product is cheaper elsewhere.
I wouldn't even bother looking at ar or ak stuff at this show, though. Prices are going to be stupid.