They just changed this recently and it's quite annoying. Until a couple days ago there was a way to search listing from all the countries which would include those who don't list as shipping worldwide by marking the "located in all regions" under the advanced section of the search engine. Well the idiots at eBay have removed that feature, so now you'll actually have to check each country's eBay, or do a search by each individual country to pick up searches for sellers that don't mark they ship worldwide! Why in the world would they remove that?
Edit: Well it looks like internet censoring has begun. I go to different eBays run my saved searches which used to give me all regions and it redirects me to eBay.com!