We purchased our (overpriced) pastel banana boi from a reptile specialty store near us because we wanted to establish a relationship with a knowledgeable hobbyist who could assist us as we learned to care for our BP. We also have a great many general pet shops near us. Overall, the care of their snakes leaves a lot to be desired.
If you can't travel and are reluctant to ship, check out Craigslist. In our area there are always at least a dozen BPs for sale. Some from amateur breeders, others from owners who need to sell for a variety of reasons. The latter usually offer the snake and habitat for a small 'rehoming' fee.