a T8 (48" x 24" x 12" L x W x H) runs $150 plus shipping and any other add ons (locks, viewing lights, etc.) They aren't cheap but will last your snake for life.
My favorite feature is that they can be set up to house 2 snakes...
You could have them put 2 thermostat probe slots (one on the bottom left, and one on the bottom right and use 2 strips of flexwatt to heat both sides individually (so you could have your Bp in one side and your BRB in the other!) with a divider in the middle making 2: 24" x 24" x 12" cages