A quick google has thrown back baggage services costing in the A$250-A$400 range. Takes 5-7 days.
Fedex quote S$200
Be very careful to check that everything is included so you're not going to get stuck for additional taxes or duties on arrival.
Also, I suspect 20kgs is a bad amount to take as lots of the handling costs will be fixed whether you're shipping 2kgs or 200kgs.
If you haven't booked already, might be worth shopping around to see if you can get a better deal with a carrier you might not have considered initially. Might even be cheaper to fly from Johor.