Ok, got a reply from the shipping guys re: insurance:
For insurance purposes, we have to verify that we've used "due diligence" in tracking down a missing package. As long as the package went out with a tracking number from here, we'll have some sort of record on what the declared value was, and that can be submitted to our insurance company. The insurance company pays us the declared value of the package and it gets refunded to the customer.
Notes- the customer is still responsible for paying their import duties, and refusing a package and it getting lost in the mail back may not be covered. Also, shipping out $1000 worth of cards bought off-site and shipped through our mailbox system while asking us to send it as a "$20 declared value Gift" will net them a $20 refund if it goes missing. If they choose not to give us a declared value, we use a formula based on the book value of the known cards in the order to determine a value (that formula is usually me looking at the high book value of what we know, and taking 1/4 to 1/3 of that as the actual street value). If they are sending items out Priority to Australia and do not check the button for an International address (which adds ~$10 to cover the additional postage), there is a chance it will be downgraded to First Class shipping with basic tracking. Any order over $200 internationally should be shipped by the customer at Priority or higher shipping to ensure they're covered properly.
I hope this helps.