How much would the cost/insurance be on a 90s Jeep Wrangler?

I am 15 years old and I am getting a license and my first car next April (2012). I want to get a silver 1997-1999 Jeep Wrangler with an automatic transmission. My parents aren't paying a dime for the car itself or for the insurance. How much will I need to buy the car, and make per month to keep my gas tank filled and my insurance paid for? Thanks so much :)