I think Coinabul should send back 50% to the buyer to split the losses since the USPS are dip shits.

Edit: Or 100% if it wasn't in Coinabul's Terms of Service that any package covered by insurance that was lost in transit and not paid for by the USPS would put the buyer at fault.

I think at least 50% should be refunded either way. You're the one making profit and providing a SAFE service so you should take the fault whenever the buyer doesn't receive his product, no matter what.

Up until the item reaches the buyers hands it should be your responsibility unless stated otherwise in the Terms of Service.