You can take the train commuter to the stop before KLIA, then get a ticket for the remaining trip to KLIA. Adds 30 minutes, but a lot cheaper.
You mean the KTM line? What is the name of the stop? So I just want to make sure I'm on the same page as you, take the line to that station, then get off and swipe my Touch N'Go card, buy another ticket on the same line to KLIA?