What can I say to make them let me have one?
"I have researched the subject extensively, and have determined it will cost X dollars per month to feed the snake, X dollars a month for lighting/heating, and X hours feeding and cage cleaning. I pledge to totally fund and conduct all the above-mentioned operations, and in the event of breach of contract, I will not ask you for another reptile as long as I live under your roof. An animal is a big responsibility, and I am prepared to take on that responsibility. My grades will not suffer and I won't turn to drugs. Signed, Your Offspring."
At least your parents are considering it. I was not allowed to have a snake (my mom didn't like them).
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Chris McMartin
www.mcmartinville.com
I'm Not a Herpetologist, but I Play One on the Internet