Stephen, as Timmeh said, try Hornsby or Lincorp (Parramatta Nissan), they'd probably be your best bet if you end up needing to buy through the dealer network. I know the Lander Group (in Blacktown) used to do import parts including Nismo stuff, but not sure if they do any more - they used to advertise in HPI magazine, even!
I'm gonna try and install FAST on my laptop sometime this week, will see how successful I am...