Greetings:
Not narrow gauge, but in October 2016, Yreka Western #19, a standard gauge 2-8-2, complete and in fair, but operable condition sold at auction for $400K. I was there bidding for Valley Railroad but could not beat The Age of Steam Roundhouse (read: Jerry Joe Jacobson).
Also not narrow gauge, but in October 2008, I bought (on behalf of Valley Railroad) a badly worn and fire damaged standard gauge 2-8-2 sold at auction for $100K. It is now Valley Railroad #3025, one of our main locomotives (after $50K for transportation and a $450K rebuilding). In this case, I had to come home with another steam locomotive to replace our No.97 which was coming due for a 1472 Service Day Inspection and other major work.
Brian is right, and an auction is the perfect place to see those conditions in action.
J.David