I don't have a Sherline (I have a Taig), but yes it appears that most edge finders/wobblers are 3/8" or 1/2" shank diameters. To start out I would buy a manual double ended edge finder like a Mitutoyo 050103. The conical end is handy for finding the center of small holes.
Once you get more experience with it, you might want a smart probe/edge finder, since you are using CNC.