Usually, how much is door panel rattle repair? 1992 300D 2.5 turbo

[ktlimq]

My right rear door panel rattles when I drive on rough road. (Occasionally on smooth road at specific speed and acceleration. But this is rare.)

I put foam (wax applicator and cut shoe insole) between the side of the rear seat pan and the door panel. I test drove the road on which I had rattle. Now it does not rattle. However, it does not look nice. When I open the door, the yellow Meguiars wax applicator can be seen on the inner door panel.
Furthermore, it is likely that someone who get into or out of the rear seat kicks the foam off.

It is not permanently attached. I put removable tape (3M Magic Tape) on door panel. Then put 3M double stick tape. Then insole and wax applicator.

I asked an indi for an estimate for door panel rattle repair, but did not get specific answer. He just told me that it is $79 per hour, however long it takes.

How much is it usually?