oh, forgot some more factors: California is generally the most difficult place to get construction projects drawn up, approved, and permitted in the country. The regulations, fees, and the time cost involved in getting a project from dream to finish is so large that they have to charge so much to break even.
Bubble or not, California will always be expensive than other states under this and other factors.
Construction of a major subdivision often takes about 10 years or more in California. Other states this process only takes a couple of years.