Not sure about musical instruments, but I’m an avid buyer seller and repair minion of an item we are forbidden to discuss here. Anywho before the advent of social media, I can’t tell you the number of times I answered a classified with one or more of those items for sale, place a call and find out they have (for example) something worth a couple K and asking $500. Most times it’s a family member of a recently deceased relative with no clue what they have or what it might be worth. on the flip side, I also saw quite a few worth a couple hundred with an asking of 3~4 times that because, “they looked old”. I always told those who were about to hose themselves what their piece was actually worth and then made an offer close to that amount. I could have had some seriously valuable pieces for pocket change, but I have to sleep at night. I don’t mind making a little off a hobby, but I can’t bring myself to just screw someone who is just trying to close a chapter on their life.