A generic PDA, running PocketFMS for around EU150 annual subscription, works for me.
It has Australian airspace, waypoints and Wx can be downloaded. (haven't tried that yet)
(I haven't tried it on any cheap, large-screen automotive-oriented-hardware yet, but that is an option)
I refuse to pay upto AUD 2000 for an 'aviation-style', non-TSOed chunk of GPS hardware. The *hardware*, repeat *hardware* is not, *that* expensive or substantially different from the automotive units.
The aviation-oriented software *is* different from the terrestrial version, and the aviation market is smaller, but for a long time I've believed that what the market leader charges for their aviation products is excessive.