The more regulations there are in a specific location, the more expensive housing is. California regulations are much more onerous than other states, and so there is a built in premium. True, Bakersfield, Inyo, and all these inland cities of California do not have $500k homes to the degree San Diego does, but they also do not have the same regulations as La Jolla.
As for the cost that regulations add to a property, I do not believe it is in the $100k (maybe in the coast communities) and up but certainly I have seen regulations add an additional $30k to $60k to an SFR. Certainly in places in the coast where you cannot lower the per unit cost using economies of scale, an additional $100k is believable. $200k? Probably not.
I am not saying that these regulations are the only cause of expensive housing here in San Diego and California. However, it is one factor that will continue to keep home prices up in California.
