i have the rear light lenses for a 3 series which are the part you need for fitting rear interior lights in your zs as seen in this thread
http://www.themgzs.co.uk/vb/showthread.php?t=11707
im after £10 + postage as these ones are currently £14.99 EACH on ebay i just dont need them anymore.
the ones in the pic arnt mine but are exactly the same and in perfect condition. also there not as dark as they look in the pic