ParksVictoria is the local authority:
www.parks.vic.gov.au/water-management/moorings-and-berths/annual-mooringsW'port is very tidal, which might be OK or it might be hassle. There the closest moorings to you will be Warneet (swing moorings to buy) or renting a berth at Yaringa marina or the Hastings marina or buying a swing mooring there.
In PPB you might have only Moordialloc, Mornington or further south such as Mt Martha or the Rye area, but a bit exposed.
Ebay and Gumtree might be the best way to find moorings for sale, otherwise paper notices stapled to notice boards. Websites for the marinas, but it depends on the budget too.