The price is more than fair for a two year old healthy female.
BRB juveniles do just fine in tubs and yes, since they need the higher humidity it will be easier on you to give her the appropriate environment to keep her healthy. They do like to climb though and adults can get up to six feet, so start saving now for a nice PVC-style 48"x30"x18" display enclosure to show her off if you want.
The biggest issue is heat, you want her to run 75-85*F, never higher than 85*F ambient. Since they run cooler than most snakes you need to feed lightly and less often than your BP's. By the time mine are two years old they're on 14-day schedules, with the prey leaving a minimal lump.
Also BRB's are never hatchlings, they are neonates since they are live-bearers.