the paint is the only supplies required...
supplies alone for an entire car can run upwards of a grand. Unless you go to MAACO, but they won't even sand your car down first.
Kevin is right, unless you are taking it to someone that is bored and going to paint the car in their barn, 3 grand is not going to include stripping the entire car. Which isn't neccessary. However, even without stripping the entire car down to metal, there is a huge amount of time spent on prep. If someone isn't willing to spend the time to prep a car right, you will never be happy with the end result.
BTW, 3 grand for an entire car, just a solid color, nothing special, is an average price. The people on here that paint may go under that, but that's hookup territory you will be entering.