"Minor" can be a little weird to define. Technically in Texas you can be tried as an adult at 17, and I know it's younger in some other states and countries. Personally I would consider 14-16 a fine age for purchasing your own pet. I think what's more important in the situation you're talking about is making sure anyone going to buy an animal has consent from the person who owns/leases the place they're living in. There are 30 year old's that live with their parents, and if they bring a snake home that Mom says has to go is that any different than a 14 year old doing the same thing?

As private sellers, it's up to our discretion who we sell to. An irresponsible buyer is an irresponsible buyer regardless of age, it's our job to identify who's who.