It's the cost of the molds that keeps anyone from doing them. They would need to sell at least 100 sets to justify making them. IF, it's not a exact mold, the other parts that are made won't fit.

Get a body shop/sheet metal shop or welder to replace/add some metal on back side where it's rusted out, then fiberglass over the area. Bondo fill the rest & sand down.
db