There was a company on eBay selling replacement seat skins, but I don't know of anyone who has purchased them. Their photos were actual Capri seats, though.
I've seen a lot of people go to auto upholstery shops & get custom work done, some of it was really incredible work. Have you looked around locally at all?
You can get racing seats, they're not too hard to install. The need a bit of work to get them to fit the stock sliders