Grannyknot, Amazon has used books as well. Got a 'like new' one of Dunn's for $9 IIRC. Dunn's book seemed excellent to me-lotta detail on family specific geneology moreso than the 'area' per se.
As Jim said, local libraries are the cheapest bet. IF they don't have it at that branch [your most convenient] they can get it thru the state association as a 'loaner' so you can read it. Even the more 'exotic' stuff thru interlibrary loans is less than $2 postage.
[May I say that the library system -as I've experienced it in the SE-is one of the FEW govt. run bureaucracies that works!
AND is usually staffed by 'customer oriented' good folks].
My library is even catalogued on-line. I usually check books for availability there before buying them-UNLESS I know I want to own them. You'll have to see how yours is set-up. There are hundreds of worthwhile books on Appalachia/GSM and flyfishing!
Speaking of which, I need to get on the road for the Nantahala:-)! Ghost