So heres an update. Rockauto refunded the card for that half of the shipment that never made it. I'm still not sure how customs played into the price, because customs brokerage fees are worked into RA's shipping. For example, if you order one cotter pin from them, the shipping will be about 21 bucks (20 for customs, 1 for the cotter pin), so it's really difficult to tell if I lost the customs portion.
Anyway, RA themselves have not been bad, it's who THEY CHOSE FOR LOGISTICS this time that screwed me.
LANDMARK logistics is a terrible company, and chose UPS to aid them in screwing this whole shipment; in the past, it's been another logistics carrier that co-shipped with the far superior FedEX.
Rockauto should be more diligent in who they delegate for cross-border logistics IMO.