Target at Hollywood Plaza SA has a returned Platinum Ultra HD TV 138.5cm (54.5") for $209 (was $499) with a note saying the speakers don't work. Which I reckon is perfectly acceptable because nobody in their right mind would rely on the built in speakers with this TV anyway. Not sure how warranty works on returned items, so you'd probably want to check this out if you're keen.
I bought one previously at $499, very happy with the quality for the price.
This one is resting upright at the customer service counter at the back.