Wow, I think the Salvos on Prospect Hway (Seven Hills) is my new favourite OpShop! I got this early 60s acetate shirtwaist dress for $8 - and its my size! (well, after I took it in an inch). I never find vintage dresses in my size (unlike my size 8 friend Kim).
Its a home-made number, but a lot of care was taken by whoever made it - I love the perma-press pleats in the skirt.