Reptile shows generally last 1-2 days and have many different vendors. Depending on the show and its reputation, the show could have only a few vendors selling mostly low-end stuff, or the show could have tons of vendors selling just about everything. Some shows are better than others in terms of clean animals/surroundings.
The biggest reptile show is the one in Daytona Beach, FL in August. You might try looking up your local herp society and finding out if there's a more local show, if you're a) anxious to go to one or b) not up for lots of travelling.