It varies greatly on the snake: if you want one that's more docile I'd talk to the seller and see what the temperament is on a particular snake you're looking at. I read that CAs/Nics can be testy as babies but on that note I hear that Hogs are one of the most docile boas and my girl can be kind of a brat. Most boas will calm down in time when they get some size on them.
Also for consideration is a Colombian BCI male: these should also stay in your range but I would recommend a 4' cage at least for these guys as they typically get larger than the other locales I listed. Most Colombians are very well-natured though and Colombians come in lots of cool morphs too. I adore my male and three females.