PC able to run Battlefield 3 for around $1,000AUD?

I have a Ps3, but I want a gaming PC to be able to play Battlefield 3. And I am fairly new to PC so yea, but been searching the web. Should I buy one or buy parts and make one? Either way, I could sell my Ps3, also I could sell my Wii which I don't play. So something for around $1,000AUD that is decent.