Yes the price of CA state parks has risen dramatically over the past several years. You could have been down the Coast in Silver Strand State Beach which is an asphalt parking lot, but now with hookups. It would have cost $65 a night there for a beach site and $50 for one a few rows away from the beach.
If you are coming to San Diego and want good campgrounds without paying the price of the State Parks, check out San Diego County Parks. None on the beach, but some nice camping parks and many are close to the attractions such as Sweetwater in South Bay and Guajome in Oceanside.