Believe it or not I use a Vitamix. I grind and sift a few times. Meaning sift out the fine and re-grind the coarse. Plus if the grain are frozen they grind up more easily
Are you thinking about hand cranking or electric?
I was thinking of hand-cranked; in case of Zombie Apocalypse ;-)
I think I recall seeing one you can hook up to a bicycle...
-JT