My wife and I collect antiques and while we were rummaging in one store my wife said, "Hey, wouldn't that work for crushing grain?". At the time, I was just in the process of gathering/building equipment to start brewing so was a little hesitant to buy it but for $60 I thought I couldn't go wrong. It looked pretty rough when I brought it home (first photo), but another $10 for sandblasting, a coat of paint and a new board it was good to go (second photo).
It works great. I read somewhere that burr mills might shread the husk too fine but it's absolutely not a problem, they are either whole or split in half. It is fully adjustable and for being a century old it probably has another century of use left...it's a tank. The downside I've found is that you cannot use a feeler gauge to measure the size you are crushing; you need to "practice" until you get the crush you want.
So, keep your eyes open in second hand or antique stores. I've seen several more after this one, although most of them are "prettier" and more expensive. Most of them are also manually operated but someone saved me the time and expense of having already motirizing.