I'm still a teenager living with my parents, so I have to wait until either I get good grades, it's my birthday or christmas, or I beg and plead for something.
Why not do what I did at your age: mow lawns and snow blow driveways.
I sent out flyers with what I charged for what sized area. Then I could pick the yards/driveways that were fastest on a route. Every client knew I was in schoold and that they waited for weekends or evenings. It didnt take much to afford the hobby.
Had a paper route when I was 12, been working since. Turned 16 and went to work busing tables....worked throughout jr. high, high school, college, and now it seems thats all I do.
When I was in High School, it was all about the grades. I realized that my parents were more than willing to indulge almost any hobby I was interested in as long as my grades were good.. (my brother managed to weasel his way into flight school just because he got an A- in Biology..) I'd go for the good grades.
Besides, that chemistry homework can be worth while when it comes to fiddling with water chemistry.
I got a 13 year old who makes money doing lawns, picking up poop, and baby sitting. She is a work horse. buys her own cloths etc. yeah, if a 13 year old can do it and carry great grades.... anyone can!