I’ve seen Troubadour I’s listed at $900-$1,000, but that’s assuming they’re in great condition. For example, have the levers been regulated? If not, they may not give a true semitone. I have one myself and it was just regulated and restrung. What a difference!

Did some more research in the meantime and found Troubadour I’s going from everything to $799 (Bernunzio) to $1,500 (Atlanta Harp Center). The latter price seems very steep to me; perhaps they did a lot of work to put it into salable condition? Bernunzio is more of a guitar place and their claims that the harp is in excellent condition–well, they probably wouldn’t know.

Your Troubadour (3842-C) is a little newer than mine (3585-C); I’m guessing late ’70s or so. The Troubadour actually goes back to the early ’60s, and the earliest ones had hooks rather than levers and had only 31 strings.

As for a fair price for your particular harp, it would take an examination by a harp technician or experienced player to tell you. Regarding where to sell it, google “used harps” and you’ll get a number of places. If you offer it without the examination I mentioned, then you’d do best to keep your price on the low end.