It's probably not as much of a scam as it is a buyer who didn't pay attention and potentially sent you the wrong address. I'm also questioning the buyer's sanity. Who spends that much and doesn't even look at the tracking updates?

A few years ago, I had a buyer provide me an incorrect address (through both eBay and PayPal) and USPS did a "return to sender" on it due to the mail forwarding service expiring (usually expires after 12 months). Apparently, the buyer moved a little over a year earlier, set up USPS forwarding, and never bothered to update his new address in eBay and PayPal. He raised hell, said it was a "glitch," and demanded that I pay for a second round of shipping. When eBay decided the case in my favor, he went silent.