I think Z3's are quite cheap to repair and maintain to be honest.
Had an SLK350 and had to go to MB for a shim replacement in the autobox, So Engine & box out (No idea why the engine had to come out) replace shim and re install.. Just under 7 grand.........Warranty but imagine if not,
I can replace my gearbox in mine with clutch while it's out...What £500???? Give or take..