I love my BRB, and though it's a little more work to take care of compared to other snakes, it's not that bad.
They require very high levels of humidity at all times, so that's one constant thing to look after.
Youngsters, for the most part, can be quite nippy. Mine has popped me three times in the four months that I've had it, but not in a long while. From what I've read on here, most don't seem to bite...I just got the a$$hole out of the group...lol It just seems to get a little honery when shedding or woken during the day. They are nocturnal, btw.
Aside from that, they are awesome. They don't get that large, and once hand tamed, are very personable snakes. They also seem to like to burrow, so carpet for substrate is a bad idea. As far as Columbian or Argentine, I don't know. I've got a Brazilian, and I've never mingled with the other two types. I got the Brazilian b/c I loved the color they have. It's all about personal preference.
I'm sure there are others on this board that can direct you to reputable breeders. I know Bob Clark breeds them, but I don't know if he has a clutch presently or not. There is also another gentleman that frequents KS that has some amazing looking rainbows, Jeff something-or-another. Good luck with your choosing and keep us posted.
My Rainbow
_________________
Confuscious say:
"Man who run in front of car get tired, man who run behind car get exhausted."