Search for reptile classifieds for your state. You can also put up a WTB ad. Also, enclosures aren't offered all the time, you have to check every few days. Since your snakes are small you have time to be patient and wait for a deal. If nothing pops up at least you've saved up the money to buy new in the meantime.
That's what I have all of my adults in. Even if a BCI did outgrow it eventually, it would take quite a few years.Also, an adult RTB would be fine in an enclosure of just 48x30x18? I was always told to have at least a 5-6ft wide enclosure. My RTB's aren't really big climbers, I don't know if its because I don't have any branches or anything to climb or they just like to be in their hides.
36"x18"x15" would be fine, just not a glass tank.Also what kind of size would be perfect for an adult BP? I was going to get a 40G Breeder until I decided to get one of the different types since glass tanks aren't being so awesome with humidity and heat. So around the same size of a 40G breeder just shorter in height I assume?
Thanks for the help everyone!