Hi Mark. I have spent a lot of time researching this and have had very little luck.
I think you will find that Sumeet grinders are electric, which is not what your request was. However Sumeet are good and operate like most Kenwood or Moulinex machines etc. The little handle on the top is for scarping/mixing the stuff that sticks to the side or won't sink. Are you after a grinder that does not use a whirling knife blade to smash the spices? (As I mentioned in an earlier post).
The proper (professional) spice grinders start around ?1,000+. The most efficient grinders ar Burr grinders like espresso grinders (you could try getting a seconhand one of these off Ebay). If you do a search using Burr, mill, flour, grinder etc as key words you should come up with some US manufacturers who make both electric and manual millers. They are used in the States to grind cornmeal for Grits etc., for the home and commercial user, so they do grind finely. I recall they were made by a couple of farm machinery manufacturers.
If you are feeling fit the best type of manual grinder is the Granite slab and roller, which is the most common type used in Asia. You can get these from Asian supermarkets.
It will be interesting to see if anyone else comes up with a solution.
CP