Like the others are saying, you will probably have to replace everything you buy just for growing out of that size. Helmet, shoes, bike, wetsuit, etc. Unless you have a rich uncle, buy used or inexpensive gear. If you can find a decent older bike, you may be able to sell for what you have into it when you outgrow the bike. Save your money for when you stop growing. By that time, you will know exactly what you want.