I found this, for $5.10 + shipping:
http://www.buhl-electric.com/store/p/2427-TC-41A-Bayonet.aspxWhich would appear to be the only one produced, because extensive searching turned up nothing.
They list Australia under the shipping thing, but if you hit "go" to estimate the cost the option to proceed to checkout disappears.
You can get to the checkout with your country listed as Australia, but I have no idea what happens if you place an order with an Australian address. You could try finding someone who carries them who DOES ship to Australia, or you could try finding someone in Australia who would be willing to order them in for you.
My suggestion, if they don't ship to the Australia, is to find a mail forwarding service in the US that does, and get it shipped there to then be shipped to Australia. Bongo does this, not sure how much they charge though:
https://bongous.com/I really tried my damnedest, but bayonet socket splitters seem to be incredibly rare.
you could always do this:
http://www.bigclive.com/hamster.htmOn a serious note, you should probably be careful as to how many amps you draw out of a single socket. I'm fairly certain the lack of bayonet-type splitters is due to their usual use: confined spaces, and portable 12v systems (cars/boats/motorhomes), where drawing too many amps could result in shorts, burnt out electrical components and catastrophic fires.
