I already had 3 phase installed and it was a shortish run (6 metres) from the panel to the garage.
IIRC my sparky charged me about $1300 - $1500.
there is no need to be a tradesperson to walk into a wholesaler. I have never been refused service. TLE, Turks, Ramax, one of these will be in your area.
The closest thing to a supercharger network in WA has just doubled in size with a Bunbury charger installed
We also have a unique take on destination charging here with the Perth city council installing 32A 3~ outlets in its public car parks for EV charging.
Plugshare is now saying there are 5 DC fast chargers in WA. 2 x in Perth plus Bunbury, Bussleton and Margaret River.
Last week there was only one.