score:4
Found an airline called Eastar Jet which offers flights from Incheon, which is Seouls primary airport. There are normal
and discounted
fares, a normal one is 260,000KRW which is a bit over $230 and a discounted fare is 99,500KRW which comes to about $87. These fares are for flights to Narita airport in Tokyo for April 2012.
I got all the way through to the Payment
page with a discounted fare which means a discounted fare applies to anyone (note that I didn't find out why discount is offered).
Hope this helps.