Electone Dreams... Part VI

So my search began.  Scouring through any information that I could find on the Internet I came to learn that there were certain models in the Electone series that were based upon the technology that Yamaha had innovated in their GX-1 model.  Keep in mind that I have never been a big fan of Yamaha until recently.  You see, Yamaha in particular has a history of developing these massive prototype / concept instruments at a loss and then incorporating this technology into their more accessible instruments for the general public.  I can't help but respect this approach.  From the GX-1, there are several Electones that seemed to have the same synth engine.  I was in particular interested in the E-70, the EX-1, the EX-2, the 6000, and the D-85.  Now for the real problem...  how to find one?