I think you have to realize that on run of the mill flies you can't compete with the cheap overseas labor. You have a good idea with the local fly shop. But you need to go to towns around you and sell to all the fly shops. You won't make any money with one shop. Even these shops won't pay a high price for a Woolly Bugger. Why would they buy from you when there are wholesale sellers that import hundreds of flies at a time. Maybe even thousands at a time. There price per fly is really cheap.
Now if you have some special flies many big shops like Kaurman's will sell private label flies but there are top of the line flies that come from tiers with world class reputations. Even then I wonder if they tie the flies themselves. Just for instance, Bob Clouser sells his original Clouser minnow for $2.95. Because it is sold by Bob people will pay top dollar. You regular fly fisher on a budget won't pay that price. So until you get a name like Clouser or Barr or Whitlock you won't get top dollar for you flies.
Here is one area I think you could work with. Saltwater flies are expensive. My local fly shop have some in the $5 range. A small saltwater fly shop may be a target for your flies. If you are not a saltwater fly fisher you will lack the knowledge of what to tie.
Another target is to sell a group of flies for Alaska, or Montana or some target area. Lets say you advertise for special flies for Alaska. You sell packages of flies for the trip boxed and ready to go. To do this you need some knowledge of the area and that is hard to come by.
To make this work you need a web site and some money. It is not easy to do and there are other people doing the same thing. To make a living it will just be plain hard.