How to convince parents to send me to public school?

I've gone to a private school my whole life. My parents want me to go to a private high school. I do too, it's a great school and I really, really like it. But we already don't have enough money to pay our bills because of tuition (mine and my brother's). This high school is twice as much tuition as they are paying for my middle school, and we really can't afford it, even with financial aid. If I go, I would have no Christmas presents next year, which I really don't care about. The problem is that my brother wouldn't get any either. He's nine, and he still believes in Santa Claus, and he would be devastated if Santa didn't bring him any gifts, because he's really a good kid. Not to mention that he wouldn't get any birthday gifts. I really can't go to this private school for the sake of my parents and my brother. My parents are dead-set on sending me there, though, and I don't want to be the reason we go into even further debt than we are now, or the reason my brother doesn't get any presents. How can I get my parents to send me to a public school?