I’m not sure how the situation has changed since selling used audio used to happen through newspaper classifieds. That’s how I bought and sold my gear in the 1970’s and 1980’s. One has to use common sense. I look at something like PayPal as being like exchanging cash like in those earlier times. Currently, I insist in talking on the phone with the potential party to see if they are knowledgeable and an enthusiast. If not, I pass.