I'm not sure what they cost in the States, I saw a baby in California that was being sold for $195.00. (I spent A LOT more on my adult females here in Switzerland (closer to $600.)
They are beautiful snakes, especially the Brazilian and Peruvians. (The Columbians are a rather dull brown and not so pretty IMO)
You'll probably get conflicting views about their temperment. Bitis Gabonica has two and they are really sweet. My girls tend to be a bit more challenging (Talyn bit me 5 times and Q bit me once), but I bought them as adults and they were not used to handling. (Q may even be withc)
They are not as good tempered as boa constrictors or ball pythons, and don't like to be passed around to friends. They will tolerate quiet handling, though. I've found that they get more nervous in bright light and mine have really calmed down since I took out the florescent bulbs in their terrarium. I also dim the lights in the room when I take them out for handling and usually handle in the evenings now with much better results.
Generally they are not recommended as first snakes, partly because of their temperment and partly because they have special humidity requirements. This can be managed though if you really want one and get the right set-up.
PS --They are also VERY powerful constrictors and should not be put around your neck!