Also consider the fact that in being only 14, you will most likely need a new frame in the not too distant future anyway.

With that in mind, I would keep an eye on the second hand market and keep your focus on the componentry attached to the frame. Do your research and keep an eye out for something with close to what you want and run with it. When it comes time to go to a larger frame, you can just transfer over all the good bits.

When I started, I wanted at least a good crankset. I got a great ebay deal that included Dura Ace hub wheels and DA crankset. Those bits are still kicking around on my current ride.