Most interstate buyers would take the drive option, but im assuming your fresh out of time and need to ship it back...
In which case just contact a few car transporters, thats "car transporters" not "the transporter"
Click below, these guys are local (Ipswich) and shipped a GTR for a family member years ago to Melbourne...
http://www.coastlinevt.com.au/
Edit: I should add some futher details, I cant tell you cost as it was part of a shipment of 6 cars heading to Melbourne all for the same show.
So the price we paid was very low, as it was a bit fo a bulk deal as such.