Matt,
I have 2 new and unused M3's. They are the ones that come in the Ninco M3 set....I bought it for the track rather than the cars. All I have done is glue the bushings and lube the gears...not even trued the tyres yet. As set cars they dont have boxes but I actually have a few spare empties so can even chuck one of them in too (albeit fly, revell, spirit or summat).
Each has run one lap of my track to check everything was working ok and they have sat in my cupboard ever since. One is white and the other silver/black.....can't remember much more about em but can take a snap or two if you need. I'll quite happily swap or sell if you want one. Just send me a PM.