1) Don't know about ETBs, but for GTPs for an adult you'll want an enclosure around 24" high -- you can either do a cube, or have something a little longer like 36 x 24 x 24 ...
2) Never kept ETBs, so I'll just tell you what I've heard, and that is that in general, chondros are easier to handle. But both of these snakes are display animals, and shouldn't be handled all that often...
3) Ignore locales, unless you plan on breeding for a specific locality... then you'll have to track down a breeder who has actual documented animals from that locale. What you want to do is find a breeder with some nice CBB babies, and pick one from parents that you like the look of...
4) Order Greg Maxwell's new book (Scotty Allen has some for sale up here), and go to
www.chondroweb.com -- it's a great forum full of chondroheads who will be able to help you out with your questions etc...
5) I don't know where you saw a baby for $450, but you definitely don't want that one. It's almost guaranteed to be WC... CBB babies in Canada go for $700-1500. On the upper end of that scale you'll find ones that are being selectively bred for high yellow or such... There isn't too much of that going on in Canada yet, down in the states there's some really stellar chondros being bred. If I had the money, I'd totally bring up a pair or 2... If you go to chondroweb.com, you'll meet a bunch of the big breeders down there, and get to drool all over their animals
6) I find that spraying for 30 seconds - 1 minute each day is pretty good... they don't need constant humidity, it's actually good for them to have a bit of a drying out period.
Hope that helps a bit Simon
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Jen