First thing is check to see if the powder guy you're using does have an oven big enough. Some coaters have a heat light that can melt the powder, but only small areas at a time. It works but is not a good job. I think this could be the reason he's charging $200.
I have a good friend who has his own powdercoating business and have worked there helping him out now and then. He never applys more than 2 good cover coats. He always heats the part up first so it can out gas as well. His oven is 6'x6' and can do rears, bike frames ,4 wheels at a time, but not a car frame.
Again, I would ask to see the oven this guy is going to use.