Just a heads up… USPS international priority prices seem to have gone up fairly significantly recently. About US$5 extra for packages > 4 pounds.
USPS first class prices have not changed though. So if you can keep your packages under 4 pounds and don't mind the lack of insurance, it is now even better value!
eg. for a 3 pound package to Australia:
Priority=$36.20
First Class=$23.50
ps. note you have to pay an extra few dollars to get the insurance with Priority mail (and it is not available at all with First Class)

