I'm fairly certain that I still haven't seen one, as this doesn't look like an M3. (I'd say I'm "100% certain", but it seems like any time I say that I turn out to be wrong. I've learned to "hedge".)
Not that it matters, the E30 Baur convertible is an interesting car in its own right. It's not a common car in general, and here in the US, it's extremely uncommon.
All Baur BMWs in the US came in via the gray market.Baur's relationship with BMW started in the 1930s. In the 1960s they started building BMW 1600 convertibles. This led to the 2002 TC (Top Cabrio), the first BMW with the targa style roof. Baur continued the TC tradition with the E21. Even after BMW started building its own E30 convertible (which Baur designed for BMW), Baur continued to build theirs.
The Baur convertible is very different from any of BMW's own convertibles. Baur kept a portion of the roof structure, which gave the car a roll bar of sorts. You could just open the area above the passengers, just the area above the back seat, both, or leave the roof closed. It looks a bit awkward, but it's a great setup. (Jaguar had a similar setup with the Jaguar XJS Cabriolet. Another car I need to own at some point in my life.)This Baur convertible is a 3 owner car. It was imported in 1991. The seller does not give a lot of info (maybe this car has some M3 parts in it, but it's not mentioned), but includes a bunch of very clear pictures. He also includes a phone number to call with any questions.
Located somewhere in Westchester County, NY, click here to see the eBay listing.