Thanks for the reply.
Yea, I've seen several places where I can buy a frame, but no one manufactures the foam and it has to be custom made from what I've learned so far. I have a saved search on Ebay, but after you remove those that are pickup only, there's little to choose from, and sight-unseen, spending ultimately a grand on a rear seat is painful. It is what it is, but I wanted to see if there were any other options available first. Apparently not, so I'll just keep my eyes open. One will come along eventually, right?