I'd buy stuff here. When you (re)enter the country they ask if you've been on any farm in the last 2 weeks. So I'm guessing they'll be worried about anything that's been set up in the bush (or whatever you call your manicured forsests over there).

Why not fill the back of the truck with mud-consoles to sell once you get here. A 26GBP saving on the postage should see them all get snapped up.

But I digress. The GBP should give you good buying power here in Australia for camping gear. However if you go to the backpacker hostels and look on the noticeboards, you can often find car loads of camping gear being sold off cheap. Basically they've bought it off another backpacker, done their trip, and now have to sell it in 2 days before their flight departs.

Enjoy your antipodian adventure.