Advice on getting my parents to let me get a bearded dragon?

first off im gonna start by saying dont answer this unless you want to help, no negativity. im 19 years old and in love with all animals, especially reptiles, ive been begging for a reptile since i was probably 5 years old and they always say no for such stupid reasons. i am actually considering getting into the reptile business eventually, maybe opening a shop, and i cant even have ONE reptile of my own. i already told my parents I'D take full responsibility for it and pay for everything but theyre unreasonable. i even wrote a 3 page paper on why i should be allowed to have a corn snake a few months ago and my mom refused to even read it =/ i REALLY want a reptile of my own and in this economy who knows when ill be able to move out. does anyone have any ideas to help me get one? (and i cant just buy one and bring it home, they pay for my school and car so i dont wanna be a jerk) theyre just so unreasonable and wont even hear me out when i try to talk to them like a mature adult about it.