We have come out for 2 years, and were in the lucky position that my OH's company paid for our shipment, and I wish we had brought more of our stuff with us. As sunnydelight says, the exchange rate is awful, and we have found that we have had to spend a small fortune on furnishing our rental (which came with a cooker, a dishwasher and a microwave - so more included than some). We managed to get a second hand fridge/freezer and washing machine - the cheapest we found them new for was about $400-$500 each. The house we moved into was much larger than we had anticipated, and so the small amount of furniture that we brought was just not enough.
You can pick up some (fairly) cheap furniture packages if you are in one of the big cities, although the quality of some of it isn't great, and some of the big cities have Ikeas for cheap furniture (luckily, we have one very nearby, which has been very useful), although again, Ikea furniture here is more expensive than in the UK - it's handy to compare the Aus website to the UK one to get a comparison.
The little things, like small electricals and kitchen stuff also add up very quickly - we bought the cheapest stuff we could find (as we knew we wouldn't be here long), and even then it added up to a scary amount of money.
Having said all that, shipping costs are high, and if we hadn't had the company paying for our stuff, or if we were moving out here long term, I think I would have been more inclined to sell our UK furniture and buy newer higher quality stuff out here. (Mind, it is like Christmas when the container arrives - my two year old was so excited to see all his toys again!)