The Thailand versions of redbull (small square bottles & small cans)are freely available in oz! And i agree that they're much more potent than the diluted, carbonated, NZ/Aussie version.
They're available at all good asian grocery stores. In Melb, try Footscray, CBD (China Town), Richmond, and Brunswick. These places usually sell the fakes too, so make sure you take note of the red bull logo on the products, before you buy them.
They;re really cheap too, you can buy slabs for about $30 - $35. Better than forking out 5 bucks at a venue.