There are still lots of good quality older N.A. or even UK-made files out there at garage sales and flea markets. I must have 60 plus of all sizes and shapes almost all purchased for a buck or two. Even found a few Swiss over the years. Same with the handles; I standardized on the Nicholson wooden tear drop handles.
Look carefully, because some files are dirty or a bit rusty, but hardly used. Oven cleaner will get the grease and crap off, wash in very hot water then sit them in a vinegar for a day or two and the acid etching of the edges sharpens them very well.
The important thing is not to bang them around against each other, nothing ruins the teeth faster. Soapstone is an alternative to chalk. Some people clean files on a rotary wire wheel, but I suspect the wire is usually a lot harder than is found on a hand file-card and probably not good for the edges.
Found a file with a handle at each end a few weeks ago, looks like a lathe file with convex sides. Never seen one before.
Another under-rated appliance is the old hand-cranked grinder that takes about a six inch diameter stone and clamps on the edge of a bench. Get a very fine stone on one and they are good for all kinds of things. The control over speed and direction of rotation the hand-crank gives you is very useful for jobs like touching up the edges on drills, HSS cutters etc. A magnifying swing lamp helps a lot too when grinding.
