Post Office A$$Holes!!!!!

...The package was less than 100 bucks so it couldn't be insured...

No, that's not correct. USPS will, and is required to, insure at the customer's request.
If the shipper told you he couldn't insure it, something's off in his statement, because any value is insurable w/the USPS.

As far as getting brushed off and not getting recourse from the P.O., be a pain in the a$$, be obnoxious, go see them every other day, but by all means make them file the claim!!!
They are government workers, they want to do as little as possible, be as problematic to you as possible, just so they don't have to do any extra work.

Like having insurance and getting into an auto accident, claims for lost/damaged packages is what "INSURANCE" is for, make them fix the problem!!!

Mark.