We wish we could set variable rates. We can't. The simple reason is that Kickstarter's interface doesn't allow us to set variable shipping rates. So we must set one price for all international orders.
Pending our final shipping weight being <250 grams, <20mm thick (a major logistical concern)... our shipping costs are as follows:
$3.05 -- Canada
$5.53 -- USA (Light Packet, Air)
$10.00 -- International (Light Packet, Air)
+ Fuel Surcharge (varies between 5-7%)
+ Applicable Tax (too convoluted to describe here)
We took these estimated costs and picked $10 for a single book.
For perspective: Amazon charges $7 handling fee (not including shipping) to redistribute self-published books: We think a $10 shipping & handling fee remains a reasonable amount for US backers and a steal for International backers.