Generally, hand files are one of the most neglected and "beat around" tools for MOST! The exception are those who appreciate using the best they can get, as well as those that make they're living using them. Also, those who are serious craftsman and want to be at the top of the skill level.
A Hornmaker, like myself, use many files that are the more expensive types from machine made to hand-cut Japanese files made in the expensive price range of $200 to several hundred dollars each. I have two that are over twenty years old and all that I plan on purchasing. Both are as sharp as the day I first bought them.
Nicholson makes two grades of files and probably more. Their lower end line are the less expensive
that we all buy from time to time at the local hardware store, and are fine for lighter home or shop use. Their commercial or professional grade files are made for heavy-duty use and these are the one's that I keep my eye's looking for at flea markets and garage sales. Two files to keep your eye's open for, are the Nickolson #49 and #50. I like to find these older one's and I'll send them out to get resharpened. New #49 or #50 Nicholson's will cost you $50 to $70 each.
Sorry for getting off topic a bit, but thought that this might be interesting to some here and give you an idea, why hand-cut files are still around, but very expensive.
Rick