You might have a gold mine. Don't get took by buyers. There are several artistic fly tyers that tie $500 to $1000 flies
to match what they did in the early 1900. Some of the feathers alone cost them big bucks.
I guess what I am saying is make sure you understand what you want to do with this collection, it could be priceless.
I know of a guide in Toas that ties $75 to $200 flies. He works for Solitue Anglers in Toas NM. Call them up to talk to him. I am sure he could direct you to reputable collectors or individuals that could tell you the price.