There are many captive bred GTP these days, not hard to find- if you have facebook, I suggest joining the group called "Green Tree Pythons~ Buy, Sell, Chat, Trade" or something like that. It's more active with discussion and chatting than the other groups, and you can get a lot of help from keepers and breeders there if you post. ETB breeders are relatively harder to find, but Harlin Wall (on facebook too) is a great guy, and many other breeders and keepers gave me recommendations to him back when I was looking for a captive bred ETB!
Captive bred ETB are much more expensive than GTP... And getting tagged by an ETB is a much bigger deal too.
Captive bred ETB can be just as calm as captive bred GTP, just depends on the individual snake. Some can get used to a bit of handling, some will stay defensive for life. (And rare ones can be handled as regularly as a ball python, but don't bet on finding one like that... just mentioning in advance) The infamous nasty reputation of ETB is mostly from the wild caught/farm bred ones.
They're really only fragile with handling when they're juvies.