What would be a good pet snake for me?

[Maki Maki]

I have been wanting a rainbow boa, but I've read in many places that they're not very docile, and do tend to be nippy. I would love to have a snake that can stay eating rats its whole life, unlike red tail boas or burmese pythons, is visually appealing, and very docile. Also, fairly low maintenance would be a plus, but if it needs high humidity or something, that's fine. I also wouldn't want something simple like a corn snake or a king snake.
I love ball pythons, but the normal ones aren't very pretty. I love the morphs, like the pastels.
If there are any neat color morphs of a certain snake that you like and fits the above description that's under $300, please let me know!

I have been around snakes for my entire life, and I know how to take care of them, and I know the expenses of owning one can be, such as with food, heating, etc.
When I get replies, I will do more research on the specific snake, because I know that each type of snake needs specific care.
By under $300, I mean from a breeder. I'm going to a reptile expo near the end of November.