When I made my berzerker beads, what I used for color were acrylics from Wal-Mart/Michaels. The colors were: gunmetal, silver, gunmetal+black, burnt umber, and black.
I put burnt umber and black into the places where I thought dirt and grime would hide, in the recessed areas and on the tops of the beads where they would meet the dreads. I then just went over the bead with gunmetal and gunmetal+black. Next I added faint hints of burnt umber, then added silver to the areas where there might be edges [like where the top of the bead and the side meet]. I basically just added layers of these until I reached my desired look. After I reached the look I wanted, I then lightly put burnt umber and black in the recessed areas again.
Don't forget that all three beads differed in color a little. Mr Blacks are more of what I ended up with, Tracker's has more of a blue tint added to the Mr Black, and Falconer has more of a brown tint to the overall beads.
Now for an inexpensive way to make a Mr Black neckring. You could use foamies from Michaels. Cut the foamies in the shape of a neck ring and then cut strips to add to the neck ring.
You should be able to find some pretty good picks of the neck ring here: