As Allan says, they are not seen very often as they can be a difficult snake to get started. Even Antaresia experts like Peter Birch has trouble with them. Your son might be better off picking an easier python for his first. Most Antaresia are great snakes so I wont say which one to start with, just look around and choose the one you or he likes. But if he wants a really small one I might suggest a Pygmy Banded Python, this is the second smallest of all pythons. It look a little bit like a Stimsons but smaller.