Well AP will make a rack with those big tubs. How much it will cost I couldn't say, but I would at least look into it.
Is she worked about height or just floorspace? BP's being ground dwelling snakes really don't make use of anything more than 5-6 inches of cage height so if you can use shorter tubs you will save a lot of money, and be able to house more snakes in the same amount of room.
Another option would be to get an ARS rack level by level Their 80 series tubs are a good size, and they make some really big tubs as well.
http://www.arscaging.com/reptilesys.html