I know where your coming from, I wasn't aloud a snake of any kind. The best aproach to getting your parents to buy you the snake is to do your research, inform them, teach them, ask them to toake you to a petshop and handle some of the snakes that they have. Show them that you can handle taking care of a snake, that you are responsible enough. Offer to pay for it. I bought my cornsnake and payed for it all. After i got the snake i got my parents warmed up to them, and they really started to like them, I later got a ball and am now getting more balls and corns this up coming summer, and plan on breeding them some time next season!! You have to have very, very, good patience. Good luck!

-Justin