Fairly expensive? Too expensive...
I'd say you'd be better off bringing enough
eliquid to do you for the trip. Maybe one or two bottles repacked into cough syrup bottles? Of course, give 'em a good whacking when they're full of water to make sure they don't break. But in my experience, the brown bottles are more durable than the clear ones. I doubt you'd get any questions about cough syrup...
If you're really screwed for
eliquid, Janty is a good bet. Use this store locator:
ìí°ì½ë¦¬ì ííì´ì§ì ì¤ì. ê²ì íìí©ëë¤. - yes it's in hangul... but you might be able to figure it out with the maps.
Ruyan Korea might be useful too... here's their store locator:
?????? (warning, their encoding sucks but at least in IE you can switch the encoding to Unicode or Korean)... also in hangul and no maps and many stores don't list a phone number... just get a Korean to call 1577-7636.