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.