As waffle stated, you could check out Mike Snody, the guy who Michael Janich got to make the originals. Don't know if he's taking orders though.
In the way of production knives along the lines of the Yojimbo, I suspect you might be out of luck, the closest I can think of is the BM Gravitator, Snody's interpretation of Janich's design, but that's also discontinued.
After that, I'm sorry but I think the knife with the closest blade shape would be a box-cutter.