If you're not too close to the end of your auction you can revise it, though I don't know if there are some things they don't allow. You might be able to add a remark in your description that says "INTERNATIONAL buyers email me for a postage quote: I ship surface" or set it up so they can choose from slow or faster and you'll send those rates and let them decide. I had to do that when I listed overseas shipping, and I'll have to see how it goes. So far I've had someone in Canada ask how much to ship there. Not exactly "overseas," but it does require some research and filling out of forms.

SRS