How old do you have to be to buy a motorcycle in Indiana?

I'm currently (15) right now. I plan on getting a job here in a few weeks. I have figured that if I can save $200.00 a week this time next year I will be able to purchase a motorcycle. I have dreamed of riding one every since I was 7 years old, When I seen a guy on a 94 Ninja 250. I currently ride a scooter at the moment I have been riding it since I was (11) So I have been on the road for about 4 years now I know the rules of the road. Please don't tell me not to get one… If thats what your thinking don't even comment… If I was to save about $200 a week I would have around $10,000 next year. There's a motorcycle dealership (Honda to be exact) pretty close to where I live. It's about 17 miles.
The day I have at least $10,000 I plan on packing a backpack full of food and water and walking 17 miles to the dealership and purchasing my first motorcycle and riding it back. I don't like cars and I don't need one because i've already got one I can use anytime I want. I'm determined to get a motorcycle. I just need to know how old I need to be?

You may need to have a parent or guardian co-sign a purchase contract and co-sign for insurance if you want to buy a motor vehicle before you are 18. Note that you will have to also have enough money for insurance and registration.

18 on your own