OK, some crappy news from the post office today regarding international shipping.
Big bad news: the box is too large to ship to Australia, at all, via USPS (but not NZ, oddly enough.)
Slightly less (but still bad) news: combining two units together makes that package too large to go anywhere internationally.
The package is also about 2lbs heavier than I'd estimated, which raises costs $5 or so for international, so previous UK and Denmark estimates go from $90 to $95.
...why couldn't Commodore Gaming have made smaller cases!?