For this transaction, if your carrier will not compensate you for the full value of the lost parcel, you could try going to Small Claims Court.
You can represent yourself, so your only cost there is your lost wages, and the fee for the Claim is fairly low,
In future, you may consider changing carriers, covering yourself more fully with a third party insurer like shipinsurance (one-off insurance) or Hugh Wood International (annual contracts and specializing in collectibles.)