Have you tried contacting Rockwood (Forest River) directly?
They will supply parts.
I don't know how old of a camper you are referring to or what parts you need, but they may have what you are looking for. I would expect that many of the older camper parts are the same as the newer campers.
The popup I paid $5675 for in 2005 now cost over $8000. That is a 40% increase in price.
Hard to see where family camping is going to survive with the increase in cost of tow vehicles and campers not to mention the campground rates today.