If your budget it limited, don't dismiss grey imports (ie. cameras off eBay, d-d-p and so on) as they can get you great deals at even greater prices, but do be aware of what buying an import entails.
Firstly, you DO get a warranty. In the event that something does happen to your camera/lens/accessory, Nikon/Canon etc in Australia will NOT touch them but you can obtain support from an
overseas service center. The downside here is that shipping etc is all at your expense, and there is a much longer turn around time associated with such repairs.
Personally, I only ever use 'imports' for accessories and the likes; things that are much more easily replaced due to lower prices. Camera bodies and lenses (which can cost 2k+) are safer bought over here where there is support readily available.
What is everybody's thoughts on the nikon d300?
What are you wanting to know?
As a D300S user, all I can say is astounding. (IMO, the best APS-C camera out today bar the D2XS/HS which is a little out of date).
That said, it is a high-end camera and assuming you're new to photography/DSLR, I'd advise against it. This is simply because of its complexity, as well as the lack of certain features more specific to the consumer DSLR market. But if you're looking for an upgrade, it will be perfect.
Between the D300 and the 'S', there really isn't much difference hence why it was only an update, rather than a 'redesign'. Main features really are the movie function (<wank>), CF & SD slot, additional Live View, Info and updated multi-selector buttons as well as a slightly higher continuous frame rate (6FPS to 7FPS). If you can chase down a second-hand D300 at an awesome price, don't pass it up as it's still awesome.
If you are however, more of a beginner, to reiterate what has been said, the D90 will be more than enough. It will provide you with a very sturdy platform, all the functions you need as well as a more professional layout (compared with lower-end Nikons) with the addition of the 'Automatic' features that make DSLRs a little more 'user friendly'. AF in it is still amazing, compatibility with practically all Nikon lenses is still there and it still has things like the commander mode for wireless flash use etc which is pretty cool. I also believe the dynamic range featured in it surpass even higher-end Nikons!
*shrugs*
My $0.02