For a first snake I would suggest a king or corn over a ball python. They're more forgiving of husbandry mistakes and will typically take f/t feeders without any issues. Unfortunately you may end up getting a ball python that only eats live feeders because... well... not every expo vendor is 100% truthful...
Also I'd suggest taking a friend who knows snakes to save you from "SHINY OBJECT" syndrome.
Finally, look up the list of vendors who will be attending the expo and then read through https://ball-pythons.net/forums/show...g-Herps-Online to research who should get your money.