Having just recently gone through selling a fairly expensive car in doing my research really only a couple fail safe ways to do this. One is wire transfer, two is cash but you better have black light for checking forged bills. Anything printed on paper is liable to be forged so no cashiers check, on checks of any king. None of these apps such as Zelle, PP, Venmo are absolutely safe either. I ended up selling car locally using cashiers check, met purchaser at his credit union, they printed out cashiers check in front of me. I deposited immediately into my checking account at my bank, before I could withdraw any cash they had to speak via telephone to credit union cashiers check was drawn on, the teller stated she had seen too many sad tales of forged cashiers checks, thus this policy.
As for audio purchases and sales, I've never had an issue. I look for plenty of feedback and personal contact, paypal ff only when I'm completely sure. I also purchase perhaps half my items from dealers, willing to pay a bit more for the peace of mind and ease of transactions.