You're basically going from KLIA Sepang (the KL International Airport) to Subang Airport (KL city airport)
LOL.
If I wanted to be super cheap, and had plenty of time
- Express Train to KL sentral
- Take the KTM commuter rail to Subang Jaya
- Get a taxi to take you to SZB airport. Maybe RM 20-25?. This might be a challenge, but there is mall, major street from the rail stop where you can get a cab.
From KLIA, a airport cab will probably charge you RM 80, thereabouts.
If I wanted to make my life easy
- I would not have booked a flight that leaves from SZB.