I am so sorry to hear about your frustration. The USPS lost my package of vintage craftool stamps valued at $200 that was shipped from a private party in North Dakota. The last tracking location was the Richmond, California hub. Despite my badgering anyone who would answer the phone, and filing lost mail forms, it was never found, and USPS basically said, "too bad". It was insured for $50, but the 30 day limit had passed. The sender was awesome, he was going to return my $200 and take the loss, but it wasn't his fault the Postal Service lost the package. He was a knife maker, and instead of craftools, I got a beautiful knife with an eagle carved into a torquoise-colored antler instead.
I sure hope the sender will do good to you. It is a very unfortunate situation.