These occasionally show up on the American eBay. The hard part is finding the specific auction using keywords non-electricians would use to describe these plugs and outlets. "old", "vintage", "bakelite" or even "crawfoot". Be aware that there is a 30amp version that looks quite similar, but are actually a little larger.
I noticed that modern Australian outlets have switches to turn the hot wire on or off. I would guess that this is a code requirement. If you did use a vintage American crawfoot outlet, you might be able to meet this code by having an American light switch (some are rated at 277VAC) right next to it in the same box to switch the outlet's hot wire.