I buy old junk wood handled screwdrivers at the flea markets and junk stores for little or nothing. (I just like wood handles.) When I need one to fit a particular screw I pick one out of the bucket and grind it to fit precisely and then place it in a rack on the bench. Now I have a "set" of gunsmiths screwdrivers that cost almost nothing. If you grind slow and cool often the original temper is not lost. None of the handles match but that helps me readily identify them for size and application.
I use the set from Wheeler Engineering. It has almost any size flat bit you could ever need in addition to some specialty bits.
I bought a set of Chapman gunsmith screwdrivers from the Gun Room in Phoenix 37+ years ago. Lots of bits, an extension and a mini-ratchet handle for the tough screws.
there is no such thing as a gunsmith screwdriver. think about it.