Unless Repticon has changed their rules, they've always allowed outside animals into the show - it's one thing that I haven't agreed with. At least at the Atlanta Repticon shows, there's always someone walking around with a pet snake to trade or sell that walked in from the street.
One thing that I'd recommend is to do some homework before the show - print the vendor list, and then go to the BOI and just do some searches to see if any of the vendors have any bad guy thread (legitimate ones and a record of not being there after the sale, or not taking care of their customer). Make sure to put a big X by their name to not buy from them - it will save you a lot of heartache if for some reason you need to contact them again.