Paypal issue beware.

I call they said because he used some sort of mandated government payment they do not require any evidence that it was shipped back.

What type of payment is this?

By chance was the buyer Ben Carson? 

Same exact thing happened to me on US Audiomart with a Krell CD player. Got jacked for 2500 bucks. Fortunately the guy that scammed me lived a couple hours away and was shocked as hell when two of his local law enforcement officers knocked on his door at 830 at night, 

I got my Krell back real quick.

I've had an issue like this when college kid was ordering stuff using the school email/username and ISP, and paying for it with bad checks.  it was an Ebay transaction.  I didn't know it at first, had the antique radio packed up, emailed him to verify address.  He emailed back don't bother I already stopped payment on check hahaha.  I emailed back well I didn't ship the radio yet hahaha.  I traced the ISP of the email, it was a college, called them, the dean took his side.  So then I called campus security, and the local town police where the school is located.  Then things changed quick.  The dean called me back, apologizing, and they shut off the kid's net service.  Turns out he dropped out of college, was still using their free net service to scam on Ebay.  he had a long history of buying things and paying with bad checks.  so I'd advise you, call the police for that city and tell them what the guy did, because he basically ripped off your stereo.  they'll knock on his door and he'll get a nice surprise when they threaten to arrest him unless he returns it.  also call his ISP and tell them he's using his net service for theft, they'll shut him off.

I remember years ago selling a video processor to a “gentleman” up in Canada. Of course the usps took a 10 days longer than their eta. Well, the buyer had filed a claim and since it hadn’t hit yet and their tracking system was and still is horrible they refunded him the money. Of course a few days later it shows up at his house. PayPal in an attempt to communicate with him discovered he closed his account and was no longer active with them. Of course he did. It was 2K! I still think to this day he had planned this all along. He even requested economy international shipping. People will always find a way to cheat. And PayPal makes it easy for them...

I had the exact thing happen to me 6 years ago, Paypal refunded his money ($1600).  To add insult to injury, UPS refused to cover the claim, even though the receipt was marked "well packed" by the agent.  I feel for you man.