"Least expensive" and "California" do not belong in the same sentence; it's the ultimate oxymoron, almost as bad as "military intelligence."
There are "less expensive" areas, but overall, California is not an inexpensive place to live. Take it from a native: I was born and raised here, and 64 years later, things have only gotten pricier.
The "less expensive" areas are usually not very desirable places to live--in the middle of the desert; out in the mountain boondocks far from services and amenities, or in crime-ridden areas of larger cities. It's a matter of your priorities, or as my dad used to put it in a joking turn of phrase, "Youse pays your money and youse takes your choice."