I ship everywhere, too, and have to. Am a small seller here, as I was on ebay,but 30-40% of sales are international, so I don't want to lose out on that.
It poses extra difficulties, though. As others have say, it is expensive to ship, and somewhat unpredictable - I have often lost money on shipping. Since vintage items all have different size/weight, it is impossible to give an accurate quote for all countries. The lithographs I am selling right now are so easy, it's a joy, but even just clothing is tricky. Unless it is as lightweigt as a summer blouse, the mail carrier won't take it because of security issues (I could be sending a bomb, I guess...), so then the package has to be taken to the post office, which is a real hassle, if you are selling and have a day job.
Having said all that, years later it still thrills me to think of certain favored garments now being worn in Sydney (or London, or Berlin)!