I agree with junkie, but not to mention you will probably want to change what you want to do in life 5 more times before you even turn 18. When I was 14 I wanted to be a physicist, and now I'm a makeup artist lol.
However, if you're dead set on it, instead of collecting makeup now, try collecting money. Set up an account that you can put money into little by little, and by the time your old enough to even need a kit, you'll have more than enough money saved up to buy everything you need at once.