How can I convince my parents to get me a dslr for my sweet 16?

Hi! I have been doing photography for over two years now. I first started out by borrowing my dads camera all the time to take pictures. he was annoyed with me using it so Christmas '09 I asked for a canon powershot sx120is. I have read and read about all the possibilities with this camera and have been using it for over a year now. I have used the macro, iso, shutter speed and other great features that people would usually be to lazy to figure out on a point and shoot. I am now getting very serious and some people have been asking me to do business with them. I would like to upgrade to a nikon D5000 and get a couple of nice lenses. I mainly focus on nature and wildlife photography and people are astonished that these pics are coming from a 15 year old. So I asked my dad if he would get me a Nikon d7000 for my sweet sixteen and he flat out said no. I have should him my body of work and I told him I want to do this for a living. I found some great deals on craigslist and showed him but he is still stiff on it. How can I convince him to buy me one? I have tried raising money and I haven't even raised 100 dollars yet. What should I do?