Try sydneywatchguy. You’re going to struggle finding vintage stuff here in Oz, at least in a bricks and mortar sense.
There are plenty of high end shops in the cbd of Melbourne and sydney, and some in Brisbane. A few vintage shops such as vintage watch co, however nothing that I can personally recommend and they have dealer prices as expected. Most of the vintage scene is between collectors (the more special pieces anyway), with a Facebook page acting as the medium.