NEW BHLDN Georgia gown purchased in 2016 (has only been tried on a couple times). Tags are still on, in BHLDN bag. Gown is an American size 8, Australian size 12, with measurements available on the website link - http://www.bhldn.com/product/georgia-gown. From my experience, the gown fit very true to the website's measurements and would fit an Aussie size 10 or 12.
Purchased for $400 US + $145 US Shipping & Aussie Customs Duty of $60. Open to reasonable offers!