For a few of the items, especially the GPU and CPU, you can save a load of money importing from US. I've shipped a GTX-970 from Amazon and paid a whole $7 shipping charge, but saved at least 20% on the cost. If it says Prime and is shipped by Amazon then it will usually ship to Au, if you click ships to AU you tend to get a different list with different prices from re-sellers who will ship.

As an example, you could get a 4690k for $235, the hdd for $55, and a GTX-970 for the same price as you'd be paying for the 280x, or the 280x for around $250. You'll have to get the M/b from somewhere else, they don't tend to ship them but B&H might or MSY tend to be the cheapest if there's a store near you. You could build a better PC for the same price, maybe with an ssd for windows or save some money.

I've got an itx Prodigy, prefer horizontal m/b, and have run a Gigabyte r9-280 WF3 and currently a 970 G1, both have run cool and nearly silent. If I was buying a case again I'd probably go with a Themaltake mini-cube, like this but I'd prefer the m-atx version with the dust filters on the side.

PCPartPicker part list / Price breakdown by merchant