Well the water filter itself was $90AUD which came with everything to install besides a pressure regulator.
I got the pressure regulator and decent filter cartridges off a mate who's a plumber.
The way I was told to use this filter system was to run water through the system for 5 minutes when installing new cartridges to clean and to activate the carbon.
If it hasn't been used for over a day, run water for a minute through the system.
Carbon is like a sponge, it can only absorb so much. Once the carbon is full it will start leeching all the stuff it's collected back in the drinking water (AFAIK). Most filter manufactures say to change every 12 mths but the way I see it if your going to all this trouble it pays to change the filters 6-8 months.