I would also check for sales of that exact coin since then in case they have sold the coin under another name and you can also give that information to USPS when filing your report/complaint.
I was going to suggest that, but it's a really common item, so it would be difficult to prove. To do so, OP would have to search for the item, say from sellers within 100 miles of the location he sent the coin to. But he still can't prove its the same person / persons, without help from eBay, which he's not going to get.
It's unlikely it will appear here, it can be sold for at least 95% of melt value locally, which isn't a whole lot less than it would bring on eBay after fees/expenses. Reselling it on eBay is a risk that has little reward, it's doubtful the "winner" would do that. Still, that wouldn't stop me from running the search anyhow.
The Floggings Will Continue Until Morale Improves.
