i have bought at both expos and online. u save on like $50 shipping and handling by guying at a show. that's pretty cool. but the shows can be busy and chaotic, so sometimes vendors very busy. they may be answering questions from many possible buyers at any moment. sometimes u don't get to talk to the breeder, but one of their helpers.
one time resisted buying at the show. 2-3 weeks later, i called the breeder to f/u on the animal i was interested in. the breeder still had the BP and was within an hour drive of me and i was able to his facility and buy directly.