It has been my policy (after I had a similar exp. that cost me more than the auction price) to send an email and ask for a confirmed shipping address so that I may determine shipping costs BEFORE I send a total price. Also you should put in your description that S&H to foreign countries will depend on the country and the method of mailing. It sure saves alot of hasseles and a few bucks.
I think you can chaulk this one up to a learning exp. and bite the bullet. OR you can contact the buyer and explain that you didn't realize their location and ask for more bucks for mailing.
Richard