Any decent fastener shop should have a good range of stainless gear, I got mine from 2 different Adelaide stores and polished them myself. Take along samples and they should be able to match them for you.
Try Lee brothers in Parramatta also known as "the nut house" yes thats what they call thenselves. I think they are in Dunlop st Parra. If they don't have them they should be able to get it for you or tell you where to get them from....