Harrolds had some Santoni's on sale when i was there a week or two ago.
Oxford also have some rediculously good value shirts, if you fit them well. They have the cotton mills labelled, including thomas mason, acorn, monti and so on for between 100-120 AUD. Depending on where you're coming from, a favourable exchange rate makes these dirt cheap.
it is designed for mobiles, but has all the 'hat' winners, (local equivalent of...