I have repeatedly purchased used speakers in my life. The biggest was the first: a pair of Vandersteen’s then-TOTL, the Model 4. I bought them from a west coast seller via an intermediary firm that handled the money (kind of a broker, ensuring the deal was satisfactory to both parties and arranging return/refund if not). They were shipped to my house in upstate NY on a semi-trailer. It was quite a scene getting them off that trailer and down the 250 ft driveway. It was a perfect transaction ... I loved those speaker to pieces.
35+ years later I’ve purchased 4 or 5 big 2-ways for the home office. All transactions were flawless, including the most recent--a pair of Harbeth 30.1s purchased from the UK. I've never been burned.
So you could say I’m wide open to purchasing used speakers. But this is a case where there really is no substitute for Paypal’s Goods & Services payment mechanism. In the case of the Harbeths, had the deal gone wrong, I would’ve had 3 parties to back up my claim: Paypal, eBay, and the credit card company. I would never buy something costing $3K or more without multiple layers of protection.
And naturally, when I sell speakers, I accept G&S payments. There's no other way to safely do this.