Here's another company i've been looking at. I've read some threads from some pretty satisfied customers:

http://herpenclosures.com/economy.html

Baby racks use the 1752 - 6 qt. box, used for babies to juvies
Adolescent/Adult racks use the 1756 32 qt box, used for snakes up to 60 inches
and the adult racks use the 1960 - 41 qt. box