Venemous for sale at reptile shows

I've never seen venomous snakes for sale at California reptile shows (most likely there's a law against it) just as display animals in venomous exhibits or being worked with in the lectures. Then I see videos of whole tables with venomous for sale in other states, I was amazed by a couple of things, the amount of snakes and all the different species available, and how darn cheap they were! Do many states allow vendors to sell venomous at shows or is it a rare thing? Is there a list of the shows that allow venomous sales? Definitely something I want to check out on a future vacation even though I can't purchase any of them, the window shopping will be thrilling enough!