I don't see why a ski company won't sponsor you. You're 15, and that seems to be all anyone needs to know.
Seriously. Why would anyone sponsor you? Do you race and rank in the top 5 of your age in a certain region? DO you free ski and have had your photos published in major magazines? Do you compete in new school disciplines and have a ranking?
Manufacturers don't sponsor for the heck of it. It is a form of advertizing. The athlete will use his/her exposure to promote the product he/she is using. A true measure of success is standing on the podium of a high level ski competition, or gracing the cover of a well read magazine.