search for Westcovinanissan on ebay, they selling genuine stuff, service is good, shipping is relatively fast. Like others said, you don't need copper if you're in Australia (no where is too cold for the copper to be used), but i will get the copper jst to be safe, only 30$ difference anyway .
you can then get an injen cold air intake. Not talking bout the power improvement as it is very debatable, one thing is noticeable is that the sound when u step on the gas pedal is awesome wif this mode (alternative version which lots of ppl in here chose is buying z tube)
then you can have transgo, pulley.
big $$ stuff is coilovers, exhausts. i prefer KW for coilovers (HKS or Cusco aint too bad), exhaust choices for me are Invidia Gemini, 5zigen Pro racer, Motordyne