I bought mine here.
http://www.cadcamcadcam.com/v-groovewheel2.aspx
But I might go with larger ones from VXB for my X and Y axis, but I'll need to fabricate my own eccentrics, or find another source, as VXB doesn't sell them.
If you download the Dual V catalog from Bishop Wisecarver, it gives load ratings and how to calculate them for the different sizes of Dual V's. The larger ones have very high load ratings, but can be expensive.
As far as fabricating, I think a drill press would be the minimum requirement. By using a fence, it's easy to get the holes in a straight line, and perpendicular to the face.