I've poked around a little bit more and done some more research. Eventually I would love to own all three but I'll probably get a pair of orange Amazon Tree Boas first and then a pair of GTB's. It would be really cool seeing them change color as they grow. It seems like both species need a cage that is 3Lx2Dx2H, although I'll definitely check this out more before I build anything. I would love to own a pair of Emeralds someday...