Wishing you best of luck to finding one soon. They are not easy to come by. I was able to pick one up on here couple of weeks ago after looking for a black one for several years.
Good luck, I found one unboxed six months ago after scouring various internet sites for three years. I found mine at UsedPhotoPro. Paid about $6K for one in great condition with slight brassing only on the advance lever. There are some individuals you may want to check with, like Tim Lei, Bellamy Hunt or Kevin Fickling, all those guys have some internet presence and might be able to tap into a deeper network.
Hi there. I have a black paint MP, 0.58, bought new in 2003 by me (not sure if I still have the box, though). I shot under ten rolls, and it has been sitting in its case, in a drawer for over 20 years! Very minty. I am strongly considering putting it in the Tamarkin rare camera auction in November, but am listening to offers as well. Or, just wait until November and try to get a deal!
MP .58