Well Ron, as they say: "everything is relative"!
Yes, California is a bit more expensive than other states, diesel fuel was about 25 cents/gallon more expensive than in Yuma Arizona this past winter, I didn't check food prices in detail compared to Arizona but the prices in California are MUCH cheaper than back in Ontario. If the state park rates indicated above are accurate then they are about $15 lower than Ontario provincial parks and we won't talk about food or diesel prices here in Ontario.
We haven't stayed at state parks in California but we stay in Borrego Springs with a state park all around us. In terms of busy/not busy, the place is absolutely quiet, quieter than back home, if we want to experience a more active environment Palm Springs and San Diego is relatively close by.
Bottom line is that as indicated California is quite diverse, you will probably find a place to stay that suits your lifestyle and expectations.