"an eBay seller who happens to live in Seoul" does not inspire as much confidence as an established business like EK, who have a well-document returns policy, although they do state that there is no warranty for internationally shipped items.
Wait, what?!?
I've gotten most of my keyboards/key-caps from countries like Japan, Hong Kong, China, South Korea, Malaysia, Vietnam, South Africa (go figure), Russia, Bulgaria, Italy, France, Spain, Portugal, UK and the US. I've only been ripped off once by a single nasty-bastard New Yorker and Ebay refunded the full purchase. Elsewhere no problems from buying keyboard gear because if you have that 43 day time limit, that usually settles any problems for you as a buyer.
I still trust Ebay more than actual Retailers, but if my local store sold Realforce keyboards and key-caps I would head down there to buy all my stuff. Unfortunately no such luck.