I sell on ebay from time to time, and don't ship internationally for a few reasons. First, there is potential scam, when item crosses the border, no tracking, the buyer receives the item, but claims it lost. Ebay will return money to the buyer no matter what, and I end up with headache only and negative feedback. Not having too much feedback in general, that will affect my future sales badly. Those type of buyers usually pop up when the value is a couple of hundreds dollars.
Second, it's always stressful one way or another.
1. Buyer from Canada asked my ones if I will ship my item to her. Sure, no prob. A couple hours after the auction ended, I checked ebay, and she was furious telling that she is going to leave me negative feedback because she can not pay, I blocked her. She sent me a few angry emails already. I simply forgot that my PayPal settings allow only domestic buyers to pay. Again, I was away from the comp only for about 3 hours!
2. The guy from Ukraine asked me if I will ship to him. I checked him first. He has been giving negative feedback to ALL his American sellers because "shipping is too high" Well, I wrote him, no, shipping will be too expensive, sorry
3. I've been selling 50 lb item, pretty fragile machine listed domestically only. I spotted bidder from the Middle East before the action ended. I stated clearly that I sell only within US, but she won the item no matter what. I could not block her during bidding because (as ebay worker told by phone) she or he listed American bank account in ebay profile. Of course, after the action ended she asked me to ship to Middle East. Nice. So, I closed that transaction and offered the item to the bidder after her for less money.
The bottom line: ebay does not protect such a small and occasional sellers like me, but they will protect pretty much any buyer. I enjoy that as a buyer, but hate that as a seller.
It would be great if ebay would make the second site just for domestic "garage sellers". No hassle, no international scam, and no fake "domestic sellers" from China.