I think you got a dishonest seller, but you hit the lottery on the USPS paying out insurance.
Maybe the USPS is much better in that regard (I've never made a claim), but the horror stories that circulate regarding many shipping insurance experiences (possibly the other players) seem to reflect that you did really well getting $100.
I almost wonder if they settled quickly in order to close out the event instead of possibly waiting and risking that you might determine the costly piece was severely damaged after a more thorough test.
-Dave