Nobody makes reproduction door panels. About the only thing that you can do (which you've looked into already), is to put something in the Wanted section. Specify year, color, material (cloth or leather). See if anybody has access to anything.
For me, it depends. Some door panels are pretty decent & I try to make note of them. Others have already been hacked (someone does not know how to remove them, or the lower corner where the map pocket is located, has been violated, because of a speaker install).
Don't know of anyone who has gone custom door panels... At least on a MKII.
Don't know of anyone who has tried to repair them, unless it's something easy, like fixing the elastic, or some of the cosmetics of the map pockets. For something like a giant hole in the door due to a speaker installation, we just put something in the Wanted Forums & see if anybody has any door panels..... :?