Hi Jay,
My Korean friend found them from people online, although I am not sure where. They're a little more expensive in Korea than other places and average, especially depending on their pedigree, around 1 million won. We got our second one when the first one was clearly lonely for a playmate, they really need to be stimulated and do get bored and fat easily. I'm not sure where you live in Seoul, but you will definitely need to walk a corgi at least 2-3 times a day. I'd have to say they aren't really apartment dogs, so that's something you will also need to keep in mind. Good luck in your search! :)

Welcome Jay!