How much should I expect for a Mechanic to charge for this job & can anyone recommend someone in western Sydney?

Being a mechanic, I'd charge about an 30 to 40 minutes labor, and about 20 dollars for brake fluid. So about 75 to 80 dollars. Thats fair and reasonable. Because by the time you clean out the master cylinder, put it on the hoist and flush it and use two mechanics it would take about a half hour. That half hour includes the use of two mechanics to bleed the system.
Anything less and I'd tell them they were dreaming. When it comes to charging I don't give away stuff for free cos I went to RGT for 3 years and did my apprenticeship for 4 years and I don't value my qualifications for nothing.

I got mine replaced at a garage at Fairfield Heights and paid $50

I have had ABS Brakes will do it for $50 plus fluid.

I know a few places use a power flusher, so its done very quickly and cheaply.