Another option in the future is American Express Foreign Currency. They had fairly competitive rates for Malaysian Ringgits (and not to mention they actually carried that currency-nobody else did). If you have a Plat/Cent card with amex the convenience fee of $15 is waived.

I checked and they do offer Korean Won, they dont quote the exact rate but they are selling a thousand won note for $1.13. Seems like a better rate than the travelex place because if you do the algebra, AMEX price works out to be roughly 952 won to the dollar. If you can get out of the convenience fee and get the cheapest shipping of $5.95 AND order in bulk (and send to Korea as needed) so you don't have to pay 5.95 shipping each time, you are getting a far better deal.

edit- Link to AMEX