I used an electric motor that I re-purposed from my drill press that was rarely used. And I added a couple of pulleys to drop the Rpm's down to an acceptable level. It was an easy conversion, fairly inexpensive and works great! You can get the pulleys and belt from Zoro Tools. Finding a motor in the 1725-1750 rpm range will get you somewhere in the 200 rpm range with the proper pulleys. If you want the part numbers for the pulleys and belt, just send me a message and I'll put the info together for you.
(Oh, and I was referring to the Monster Mill in my post.)