That type of data is hard to get and hard to release publicly. But if you play with the tool, you can see that across both HMOs and PPOs, San Francisco County is way more expensive than LA (even when taking into account a risk adjustment). So this may be indicative of a geographic market issue.

http://costatlas.iha.org/map?m0=TCCCOMP&p0=HMOPOS&m1=TCCCOMP...