I officially tried the new ITX Cheongchun line to Nami Island. The line was officially opened to public since 28th February and I rode it on 7th of March, prettyyyy new and the service still has some hiccups here and there.
You could actually take the first train from Yongsan station(Line 1, dark blue) or from Cheongyanni station(Line 1, dark blue/Jungang Line).
I rode from Cheongyanni station to Gapyeong station(nearest station to Nami Island) took roughly 45 minutes.
Fare should be 5,700 won from Cheongyanni Station. However at this moment, there is discount given and I paid for 4,000 won only. Asked the officers at Cheongyanni station, they were not sure till when though.
Gapyeong station is located at a new spot from the stop that I previously stepped out in 2009.
The taxi ride costs about 3,000 won and the entrance fee (ferry ride + Nami Island) is 8,000 won. The tourist information center in front of Gapyeong station told me it was 10,000 won but when I paid the ticket at the jetty, the officer said they still charge 8,000 won.
My partners in crime to Nami Island - Lia, Yusuf and Asma.
If you realized that there's so many routes to reach Nami Island: by shuttle bus, by ITX train, by normal train. The costs and the journey's duration differ.
More pictures in BudgetTravel2Korea Facebook.