Actually it can be less expensive to by a used Mark II and scavenge the parts you need. I bought a used KMK678 a few weeks ago as I needed a frame for a new VQ LLV I had bought. Time I sold the takeoff parts I had about $225 in frame, bolt and latch. And SS frames, bolt and latch will bring $250 - $300 on GB. I see used MK4 and MK6s for around $250. Which is what a blued frame, bolt and latch bring.