As a fellow Floridian (Clearwater) and the mother of a 15 ds (16 in January)...have you checked out insurance rates? I am amazed at how HIGH they are...even if there are only 2 cars, 3 cars is insane in our area! We are going to require our son to pay his insurance and a good portion of his car, however, we are willing to help him out with part of the insurance until he gets a job because he will be eliminating a lot of "my" traveling. We (dh, myself, and ds) are planning on sharing 2 cars for a while, as I only have definite plans on Wednesdays.
Looking back, I had to buy my first car and pay for my insurance...and I didn't get a car until my senior year. My friends were given new cars and I drove a 1965 Plymouth Valiant (station wagon...low miles, little old lady drove it...excellent shape...but still!). I survived!
Good luck with your decision!