I agree about carpet pythons and bloods. They aren't common like corns and BPs, you won't find them in big box pet stores, but they aren't so rare that husbandry is difficult to track down. They certainly are larger snakes that don't get "too big".

They aren't exactly rare or truly unique though, but in some ways that is a good thing because you have your choice of who to buy from and good resources on husbandry.

Some "rare" snake species are rare for reasons that are undesirable for many people: difficult husbandry requirements, difficult to breed(so likely only able to find WC specimens, or CH if you are lucky), nippy and difficult to handle, and often just plain expensive.

If you're able to spend a couple hundred bucks on a snake, you might check out woma pythons. B-E-A-utiful! I've seen 'em in the $350-$650 price range. From what I have read they are pretty darn easy to take care of, get to a decent size, and believe me that not every joe shmoe has one of these. On top of that they are supposed to be great handlers.