Parks Victoria are releasing new moorings at WIlliamstown right now. Call 'em up and you might (I repeat might) get lucky, if there aren't too many on the waiting list.
Public moorings are great value - a couple of grand to set up, then under $200 pa for fees
. Of course you have to have a dinghy
to get out there.
The big but is that theoretically you can't live aboard, but if you did for a couple of nights a week you'd be right.
Also try Yaringa on Western Port Bay - they have spaces and were (when I last checked) around $3k pa for a 10m boat, and you can live aboard.
If you get down Sandringham way and see Felissity (Compass 28) on a swing mooring
, give me a hoy and come aboard.
Good luck! Graeme