I think these guys should be able to help you out.
www.e-go.com.au/home.do;jsessionid=944ECA4FEF9683FBE9C3A25D94D50E4E
You'll get the best rates by sending from depot to depot; I found their prices excellent by sending that way.
I used to use them a lot, sending large boxes (600 x 600 x 600mm) for a fraction of what all the other
bloodsuckers couriers charge.
I was sending parcels all over Australia from Perth.
IMO the best courier in Australia, hands down.
I'm not affiliated with them in any way; with all the bad service from business out there, I like to promote the ones that actually do a great job/service when I get the chance.