According to the USPS there are only 6 countries with 'open' postal service with the U.S. Those 6 countries will take any package just as if it were being shipped within the U.S.

For all other countries there are a variety of package size restrictions and the fees to those countries vary greatly. As an example I just sent a frameset to China for $97. That same frameset to Australia is $350.

How many countries are there for a U.S company to ship to? For each package sent, a company like Performance would have to weigh each individual package and check for shipping rates. I haven't shipped one package to Canada where I didnt have re-quote the rate because the recipient was looking for something cheaper (less secure).

Keep in mind that each countrys own postal service is responsible for delivery of a package. How safe and secure is the Mexican or Honduran or Croatian delivery service? How many packages would 'disappear'?