Ways to raise quick money for a car?

Im 15 and can get my permit soon so I will have to buy a car. I want to buy it with my hard earned money not my mom's. I want to get a Toyota Supra. I will buy it most likely off craigslist due to costs. But I need ways to get to around 7,000. I have 800 saved so far. I know 7000 is alot but I'm willing to do what i have to do to get it. Most places around my area wont hire until 16. :/ I was thinking of maybe putting an ad on craigslist saying "Willing to do any labor jobs such as yard work, and moving heavy objects for cash". Do you think this will work?