Good luck in your search. Great guns!
Consider that the original "Standard" Model had a retail price of $37.50, they've come up a bit. I have one of those with red eagle, in near new condition. Interestingly, this particular gun is serial dated to about a month past Sturm's death. If that's accurate they must not have made the change to black eagle immediately.
Here's a MKIII with threaded barrel, I moved the front sight back and made a thread protector that looks like the original barrel.