I'm not sure if this is the correct place to put this...but...there used to be a company named SparkDrill that produced a portable EDM (you mounted it in the spindle of your mill) that sorta "disappeared". I do know however that before they went MIA they were offering plans for $100, circa 2000-2002. Has anybody seen or heard of one of these EDM's or bought/built the plans? I would very much appreciate the feedback from someone in the know.
I have seen similar plans to what you are talking about on ebay. Just type 'edm' into your search and it should be one of the first ones that come up. There are also plans for an actual sink EDM and a wire EDM.
If there were no rewards to reap,
No loving embrace to see me through
This tedious path I've chosen here,
I certainly would've walked away by now.