As most of you know, international shipping from the US isn't cheap - and if you go over a certain weight limit, it becomes cost-prohibitive.
What I can say is that a USPS Priority Mail International Flat Rate Large Box can hold up to 20 pounds of miniatures, is fairly large in size, and costs $60.95 USD. To offset that cost - and the 20 lb. shipping limit - if we hit the $5K stretch goal, all backers at the $75 Level and Higher will have the option of selecting ALL of their rewards in RESIN instead of metal. In other words, I am confident that if you select resin and are an international bidder, you could acquire all of the Stretch Rewards (including those not yet announced) for a MAXIMUM of $60.95 shipping.
All Kickstarter rewards will be sent and pressed carefully between layers of self-stick bubble wrap to ensure safety during mailing and to reduce the cost of shipping everything in standard "retail" packaging. The retail packs would not only increase the needed box size, but probably the weight of the parcel as well.
The best part is that International Flat Rate Priority shipping provides proof of mailing and is delivered normally in 6-10 calendar days.
To close, I would also like to add that I am not looking to "pad" shipping charges. If you are an International backer, you will pay only the actual cost of shipping, not anything more.
Hope that helps answer some questions!