Pricing Alphorns?

A hornist that I know is considering selling her set of two wooden, hand-made alphorns to me. She bought them some 20-30 years ago in Europe. I have played on them, and they are in excellent condition. I believe that they are pitched in F and they can be broken down into transportable lengths. I don't have the maker or model information right now but I am quite sure that they are Swiss. She would like for me to propose a price to her for them, but I am finding little information online about what they are worth. I have no idea whether there is a hot market for alphorns right now. These instruments are located many, many hours by car or plane from a major urban area so I can't easily take them to a shop to have them assessed.

Any ideas on where to find pricing information on these alphorns?I am not seeing used alphorns for sale online. I want to propose a fair price to her. (I'm not saying where they are in case somebody might try to snatch them from me!)

Has your friend sold her horns? I have a friend looking for one. I bought a used alphorn about 5 years ago and I think a used horn would be worth at least $2500. A new Stocker is $3000. A "real" Swiss alphorn is probably in G-flat, which is the traditional Swiss key. Most US players will be in F. Please have your friend contact me at tmdyess@yahoo.com if still interested in selling. Thanks so much.