Sorry, that's not correct. I post goods internationally almost every day, so I'm reasonably familiar with rates to different countries. For Royal Mail, the US and Canada are both World Zone 1, so postage prices are exactly the same. Australia is in World Zone 2 and costs a little more. As an example, a 500g (1.1 lb) package would cost £12.95 to both the US and Canada, or £13.45 to Australia.