Man that sucks. Those parts are likely gone forever.
The seller has some responsibility in this to package stuff sufficiently well to survive a trip thru the mail. I've sent quite a few odd shaped and relatively heavy items similar to those shock mounts successfully. The boxes need to be reinforced. You can't just throw them in an unreinforced cardboard box. Heck, I even sent myself 50lb of scrap lead from CA to AK in a flat rate box, but I doubled the box up and filled the empty space with more cardboard, and use fiberglass reinforced packing tape. It survived intact with just a few surface blemishes. Probably got a few curses from the postal carrier though.
