I see some people use vivariums but I am interested in a arboreal cage like the pvc ones with the plexi front door. I think the pvc arboreal cages would be excellent as they are cheap, allow easy use of a RHP, clean easy and provide great front viewing.

I dont know at what size the snake should be for a arboreal cage and what size cage to get. This the site I was looking at for a cage.
http://www.herpcages.com/cages/cprice2.html
The cages are cheap but I dont know what size could house a adult, or if I can start one in a small cage from that site. Please help me out