I hate when I have to do this, but unfortunately, the USPS raised their shipping prices again this year, effective January 27, 2013. Prices across the board have been increased, with international shipping having the most considerable change.
As always, I keep my shipping costs to what actual packaging and shipping costs are. Nothing irks me more than paying a ridiculously high postage fee, so you can trust I'd never do that to my customers!! If, for some reason, the shipping charge ends up being less than what you've paid, I refund the difference.
More info about the new USPS prices- https://www.usps.com/business/prices.htm