Kieren, sorry for the problems. I just talked to Phil and basically here's the deal - We have a program that gets the prices and options directly from the post office based on weight and location. For some reason when the order weighs more then a pound on International orders it takes out Global Priority and Airmail which are kind of important.
Long story short - we're not sure how to fix it. The best option is to do this. Creat a dummy order where you choose "Check or Money order" as your payment option. That way we'll get the invoice but no money will exchange hands. We'll then look up the actual postage and send you a new invoice via paypal with the correct price.
Sorry for making you guys jump through hoops on this.
I think I want to look into ednicia maybe. Phil and I will have to decide if that's a better option.