Cheap car parking in south melbourne near domain interchange

I am working in south melbourne near domain interchange/380 st kilda road. The cheapest off street parking is $10.30 on bank street or dorcas street, but it is always full at around 9am. Does anyone know if there are cheaper parking around the area? I know some of the apartment owners around the area will rent out their parking space, but I am not sure if there is a place that these owners are posting the ads?