This is a great spot just off the Gt Eastern Hwy 50 kms east of Perth (in Chidlow), only $8 per night single or $8 per person ($16 a double) for tents, camper trailers, campervans and small motor homes, but no caravans.  Powered sites with main water and power, modern shower/toilet facilities and campers kitchen, bbq's etc, plus water, cycling and walking facilities.  Campers do not pay the day entry fee of $6 at the gate.  Also worth a day visit if not camping, nice picnic area patrolled by Bruce the Goose and other ducks.

There is also free accomodation for limited caretaking if interested, and as well as RV's and tents mentioned above the caretaker can have a caravan with own private site, power and water etc.  Volunteer only for night period, up to midnight, no wages.  See this link;

http://www.caravanersforum.com/viewtopic.php?f=70&t=15767