Regular old Boa Constrictor Imperators are fantastic. If you got a male it would stay smaller and could be kept in a 4'x2' enclosure as an adult. At least, most can. I have a BCI and Dumeril's Boa, and while I love both, nothing compares to the amazing personality of my BCI. She LOVES to be handled and is so curious and intelligent. I would suggest a male BCI. They should definitely be in your price range....where a Hog Island may not. They are not as easy to find and as a result tend to be more expensive.