I would have thought that starsan would be a pretty standard item for a home brew store. But I'm still on my first bottle so I haven't had to look for it again. Assuming it is standard, then you just need to find your nearest brew shop.
Go to http://maps.google.com.au/ put in your address so you see it on the map, then type in home brew and it should bring up the nearest ones. It might pay to see where the nearest place to your work is too.
Or like the previous poster said, order some from one of the forum sponsors. Come to think of it, my starsan came from craftbrewer, but I visited the shop in person. Biggest brew shop I've seen.
You know what they say about Assuming - it makes an Ass of U and Ming.... wait - what?
Most Sydney LHBS's don't know their arse from their elbow.... my proper local ones still think sodium met is hip... or square - if hip isn't hip anymore.
Sponsors. Press the links up ^^^^^ there... there's a couple of sydney ones, but there's also this wonderful thing called Australia Post, where this lovely man will drop off boxes full of shit you can buy without getting up off the couch!