So far I've only been to one reptile expo and it was really small and dominated by BPs and Geckos. It was cool to go to. I know some people will haggle at shows, I didn't at this one. I paid what they were asking, but I probably will at the next one I go to since I plan on buying a BEL. I've heard that prices drop a lot towards the end of the show too.
Look at the vendors link, it will give you a decent idea of who will be there and what they will be selling.