Since you're in Australia, there's a limit to what I can offer that might be useful. International mail can be a dodgy proposition, particularly if you're just sending ONE item each to multiple countries.

Here in the States, we sometimes "workaround" through eBay, which has its own global shipping, and its own delivery connections a bit like Amazon. But I don't know if there's an Australian version of the eBay International Shipping. If there IS, you could "sell" the prizes to the winners for something like $1 and they pay eBay for shipping... and you get their internal tracking door to door.

Alternately, a mail forwarder? Again, that requires a certain volume of packages.

All in all, it's tricky. Been in the global sales biz since 1985, and in online sales internationally since 1996... and there are no secure and easy answers I have found.

=^..=