I think I should contribute.
When I still had the Z3 I wanted to replace the rear window as it was a bit perished and faded, but the actual material was still in good condition. BMW does not offer replacement windows so I inquired to then replace the whole material roof. They also don't do just the material, just sells the roof and mechanism assembly. And that goes for.... wait for it..... R76 000 excluding fitment.
One of the few times in my life I was literally speechless. I only managed to say "thank you" and hung up the phone.