Just because the appraisal doesn't use the word "worth" in the wording doesn't mean that's not the intent of the appraisal. The intent is to specify a value or worth at this point in time. In other words it's saying this is what a buyer would pay right now. In other words it's worth "X". The intent of an appraisal is exactly to describe the worth of something. There is no other reason for it. Calling it market value instead of worth doesn't change anything.

Also, if I have one guitar to buy or sell then one sale is the only market worth talking about.