I did think about doing this at one point to be honest I'm glad I didn't, it dose seem like a good idea in essence ,but what about the one time wonder clients? You know the one going to a wedding or on holiday, will you keep there packs forever? Or chuck them And Waste the good files that wear never used?
You will still need to buy loads of single files as well, because there will be some in the packs that you will use quicker than others , e.g. 180 grit might need replacing long before the 100 or the 220 on one client , and different for another, so you will have to stock all the files as singles, and have the packs for the new clients , I think you might find your self using twice as many or at least having twice as many in use!
I understand the part of the client feeling special and maybe the client would belive it to be more hygienic but my clients do not think my files unhygienic, after every treatment I check them clean and sanitize them put them away in the pot and at the beginning of every treatment I select the ones I will be using for that treatment lay them out in front of the client and I spray them with Mondo file disinfectant , that way the client knows they are clean , I am not using my valuable space on 100 files packs, and I belive it is still professional.