Yup...
You snooz, you loooz
The one I saw was an original item..had the logos and all...
The online ETK does not show a glass roof for E30 or the E36.
But that doesn't mean it doesn't exist.. Just very rare. Probably on some specialized parts catalouge.
It shows up on the E46 listings though, probably because it was an optional item when the car was first launched.
If you do manage to find one, make sure it comes with the sliding headliner, and frame to house the additional guide rail for the sliding piece. Otherwise, it's just a piece of glass....