I don't know for sure, but I think your average red blood python can go from $75-150 depending on who you get it from or the quality of the snake. I got my blood for $350 from Kara Glasgow at bloodpythons.com. But her stuff is some of the best out there.
I think a six foot female BCI could go for a couple hundred bucks, so I don't know if it's an equal trade. I suppose it depends on you and what you like. I love bloods and boas equally, so it'd be a tough call for me.