Hi,
The park in question is Ocean Beach Holiday Park at Umina on the Central Coast and run by NRMA, who have a few other parks. Yes, we have stayed there and had a great time. Yes, it is expensive in relation to other parks. To put the cost into perspective it is a Resort Park with a resort style pool with a waterside and kids area, jumping pillows and lots of school holiday activities day and night of which quite a few are free. It is right on the beach and the camping area overlooks an adjacent creek. The park was spotlessly clean and very safe as it is at the end on a road.
So if you want a quiet place away from it all with no added extras, it is not the one. If you have kids and want a holiday with plenty of activities and do not want to do a resort hotel but want to use your camper trailer then it is good.
My 2 cents worth.
Tony.