Go buy it yourself. Or go start making and saving money up for it.
Go pick up soda and beer cans along the road, cash them in, buy it. If you are not willing to do that - then you don't want it bad enough.
You are 15. You could baby sit, house sit, pet sit, do a paper route, mow grass, go shopping for the old people on your block...… you have tons of fricken options, mate. And if you can't figure out how to make money and save it now - what are you plans when you get your drivers license and want a car? Cars need gasoline and maintenance...….. you need to figure out how to buy a simple iPhone with money you made on your own. Or are you planning on attending the Senior prom with a bicycle built for two?