In 1990 I was quoted £800 for a bare metal respray on my BGT. the shell was complete, with no rust remaining and several new panels.
I didn't get that in writing, and he didn't mention anything until I went to pay, and the bill was £1,400.
He mumbled about it taking more time than he expected. The moral is to get a written quote. But you all know that.
Because this car was for concours and I didn't want shortcuts, I didn't argue, but it cost him other customers who were put off by what happened.
That was 1990. When I sold that car in 2008, the paint was still excellent. No deterioration, no bubbles.