I also received a confirmation from Tischer about the Jeff Koons car.
1) ECS Tuning also has the Jeff Koons car in stock for about $13 less than Tischer.
2) I contacted Minichamps directly to try and track down a #78 GT2 since they are NLA from BMW. I was finally able to get one at carvillemodelsshop.com for $155 (plus shipping). I just received it today. It's in a Minichamps box, not the BMW dealer packaging. Other than the outer box, everything else inside seems to be the same exact model (shown earlier).
2011.5 M3 Coupe: Space Gray, 4MY, ZCP, ZCV, ZP2, 494, 5AC, 655, and 752
Mods: Full Venture Shield protection kit, RPi scoops, Euro fog light switch, LUX V4, clear reflectors, OEM black chrome grilles and side gills, black hood vents, IND F10 M5 shift knob and boot