Found one:
http://www.wheatgrasskits.com/manual_grain_mill_grinder.htm
They also have the electric mill I own, called K-Tec or Kitchen Mill, and there's helpful into on the site.
Another thought -- a local Mormon church might be of help -- they, at least a while ago, emphasize self-reliance, etc...

Grinding your own grain is the best way to avoid rancidity. When it's ground, all of nature's protective barriers are destroyed, and the germ, the source of the oil which can go rancid, is smashed and smeared so that it just begs for the oxygen to go "off" (with?). Grind and use -- and if you need to store it, refrigerate or freeze. My first exposure to home ground flour was a friend who ground and made her bread dough, which rose enthusiatically as we watched -- I believe there are enzymes activated which are active for only a short time.
There are good home grain mills which are hand cranked, often made of heavy cast aluminum, I think, but of course require a certain amount of upper body strength (like your coffee mill). You can even get hand worked stone mills, which are kinder to the germ. I have an electric mill which is supposed to shatter the grain rather than smash it, currently out of reach. Should be a source like Mother Earth News (magazine) which would lay out all the options. (I think Samp is one brand that makes them.)
You can even get rollers to make rolled oats.

I grind my own nut flours, as I'm very allergic to certain nuts and have been poisoned by some purchased flours. I've never tried oats.

I use my blender or my food processor. Usually I do almond, walnut and hazelnut.

I grind my own flour using my vita-mix dry container. Some think a vita mix is too expensive, but they last forever and are so versatile. Concur with your experience that home ground flour is superior. Good luck!