I would not plan on buying at the expo. Get contact info for the local breeders and find someone who would be willing to meet with you to take time to get you exactly what you want. An expo isn't really a good place to do that - if it's crowded the people vending are not only talking to you but they're also spending time making sure nothing gets swiped off the table, they're talking to others, etc. Also snakes can act very differently at expos than they do normally; many seem easygoing but it's because they are stressed and in temperatures that are colder than normal so they're torpid.