bci's are great, and the price is right. Their care is simular to bp's, they just need alot more space.

Argentine boas are niiicee. They are a bit more expensive. They are pretty active as far as boas get.

If you decide you want to look into aboreals, study lots. Their husbandry is a bit more difficult then most. I would suggest an Amazon tree boa for starters there. They have simular husbandry to the ETB's but are a bit more forgiving if you make a mistake.