A cheap bush option would be Honeymoon Bay on the Beecroft Peninsular. Only a few dollars a night. Camping only. Port-a-loos. No other facilities. North side of Jervis bay - awesome area.
You can launch the boat from the beach, or at Callala Bay ramp, and moor it next to the bay (for free, on permanent moor sites).
Great access to the entire bay, great fishing, heaps of squid, lots of bushwalking, swimming, etc etc.
Only downside is lack of facilities and not close to a town if you want non-outdoor activities.
Mike