Basically, to our utter surprise, the Chinese board houses can't ship to customers for any less than US shipping. We still don't understand why this is the case. I'm sure all of us have received Chinese items from ebay or Banggood and the shipping is free. For some reason though, this doesn't extend to the board houses.
We have made a separate low international shipping cost unit that does not include the battery holder. The battery holder has pins 52 mm apart, and they're easy to get (e.g. Keystone part number 2460).
So the permanent solutions we have right now are for international backers to buy units that don't have the battery holder or to pool up with friends and buy a larger quantity so the shipping cost is a lower percentage of the unit cost.
We'll continue to try to get a better shipping rate, and if we do, we'll figure out how to distribute that savings to the backers, but for right now, international backers should plan on the rates staying what they are.