Boink,
Instead of teaching sharpening, have that as a service to your customers.
When I sell a knife at the gun club they get it sharpened free forever. I have people buy their knives from me for the price and the sharpening service that comes with it while they own it.
I get 3.00 a knife [ hand sharpened, not on a grinder ]. They hand me a butter knife and get back a razor blade.
As to a store front and stocking items, kitchen cutlery for the women [ and they'll bring their knives in to be sharpened as well, full line of spyders, blade-techs, SAK's, Benchmades, and then have a section of ERs, Striders, some customs.
Don't forget the straight blades for the hunters like Case, etc. and then some of high end like Bagwells, Lameys, etc.
My opinion is the competition is way to stiff as others have mentioned. In looking at some of their prices advertised, they are making 5-10 dollars on a knife after shipping over what I can buy them for at dealer prices.
I have people bring me their wives kitchen knives 10-20 at a time at 2.00 per knife [ priced from 3 to 2.00 due to quantity ].
Brownie