Don't worry, no matter how much $ you bring, there will be plenty trying to help you part with it, lol. Is this your first snake?
You really should check out prices for snakes that you like ahead of time...just to have a "ball-park" idea. "Pretty" is rather vague & if you don't have some
goals in mind, a well-attended expo can feel overwhelming with all the choices. Psst! do watch out for snakes with mites! they get "shared" at expos!
Personally, I'd not buy a snake with mites...they can carry diseases among snakes, so it's a health risk.
More importantly, you want to bring with you a thick styro-foam box (or "cooler") to safely transport a new snake safely home. (+cloth bag & twist-tie to secure)
Also...top priority...set up the cage for the snake ahead of time, & test it for a week to make sure the temps. & humidity are right. You want to minimize stress
for an newly-bought snake that may come home with you.
Many here look thru Morph Market, if you aren't already familiar with it. Lot's of high-end BPs for sale there, but you'll also be able to see what appeals to you.