To have an idea of the cost of living in Los Angeles, you may check the prices listed in the various sections of this website (accommodations, car insurance, transportation, shopping, etc.)

Additionally, you can have a look at the following web sites for some more general ideas.

http://www.areavibes.com/los+angeles-ca/west+los+angeles/cost-of-living/

http://www.numbeo.com/cost-of-living/city_result.jsp?country=United+States&city=Los+Angeles%2C+CA