Here are some rough estimates based on my own collecting experiences. My oldest guide is from the early 1850s. These days, I'm mostly focused on ephemera and photos.
The most valuable guides are the AMC guides from 1907-1936. 1936 is the most interesting because of the hurricane. They start at about $100 on up to around $600. The first edition can sell for considerably more, but $400-$600 is about right. From 1940 to 1963, they sell for around $40-$100. From 1966 to 1983, $20-$50. 1987 and later, except the most current edition are usually under $20.
There is less interest in non-AMC guides. Tripp's and Eastman guides going back to the 1850s can be had for under $150. Chisholm (Sweetser) guides from 1880-1913 around $50-$100. The Starr King guide was as common as the bible, so you shouldn't have to pay more than $40-$100 to obtain one in good condition, althought the price on this one tends to vary wildly. Drake's travelogue is excellent and not too uncommon, around $100.
Other guide books appear rarely, so it's hard to put an price range on them. A number of excellent guides were produced to cover a specific area or a small number of trips and lasted one or two editions. My favorites are from the 1920s - O'Kane's 1925 guide and Bradford Washburn's Presidential range guide from 1926 (with photos by Shorey). O'Kane is easy to find, but many others don't appear on the market very often. For example, it's been a few years since I've seen an early WODC guide for sale. It's tough to estimate prices on these. Good luck finding them in libraries, either, most of the old, interesting guides have been stolen from the ones I frequent.
Individual issues of Appalachia tend to be overpriced. About $5 an issue is reasonable after 1970. $5-$10 per issue is reasonable for 1950-1970. From 1930-1950 expect to pay $10-$30. Anything before that will range from $20-$50 each, with the earliest for much more. Early journals were unfocused, so do some research in libraries to identify specific issues you'd like to add to your collection. The bound editions are common, but you may have to prod a librarian to pull them from storage.
For all of these, I find that if the bookseller has an interest in White Mountain history, the price goes way up (with the exception of the Mountain Wanderer). My local bookseller who will remain unnamed charges on the high end for even the most common items. If you find a bookseller with a handful of items, good deals can be had. eBay is not as good as it once was for this, the demand is still high, but not as high as it was around 2000-2001.
