Depends on the game. Notice the "Value System" disclaimer. What games are you planning on running.
Saints row 3 and maybe minecraft, borderlands 2, hitman etc. hopefully on high settings at 1080p. For a couple of hundred more you can get this. http://www.pccasegear.com/index.php?main_page=product_info&cPath=1411_1446&products_id=20934
My budget is 1K but I'm happy to spend $100 more if needed. I also live in australia