....no offense to you, but judging by what you posted, I'm guessing you are under 16. I would recommend not getting on a bike of any kind. even a 250. Why? Because teens around your age tend to make bad judgments while driving a car, imagine if you were to make one on a bike. Read alot of the rider down post, alot of them are from driver error.

If you are stilling looking to get on 2 wheels, get a scooter. 49cc scooters these days can do about 45-50 mph and you can buy a new one for about $2000. That and you only need a driving permit to ride one (I believe you still have to where a helmet though). I know you won’t be as cool (come on, you're only 15, you have like 60 years of life still in you) and you won’t be able to corner as hard, but it the closest thing to a bike.

Just my .02's