I can't recommend a tank for an adult boa. Partly due to size, but also because keeping heat and humidity just sucks in tanks.
You can pick up a PVC enclosure for not too much money. Personally, I recommend ConstrictorsNW - Ed has some really nice products and they are made from HDPE plastic which is WAY better than PVC.
But Animal Plastics and PVCcages.com also have some nice choices.
Stick with something that is 4x2x2 as a minimum. If your boa is a female, I strongly recommend a 6x2x2. Some will say you can get away with smaller, but why would you cramp your snake?? Boas will use ALL of their enclosure space if given the chance. Since we are imposing captivity on these animals, it is only fair to give them the most space we possibly can.![]()