There is a sticky thread on workshop listings mate.
http://www.skylinesaustralia.com/forums/topic/123887-workshop-autoparts-listing/
Just to name a few there are Willall's, Boostworx, Fours n More they are all up north and Southern Hi Tech Dyno, Graham West Workshops etc down south. So depends on where you want to go and what you want to get done for the price you are willing to pay.