Looking for a fresh start in a new San Mateo neighborhood that is actually affordable? Fortunately, there are some neighborhoods that still offer affordable cost of living. Listed below are the most affordable neighborhoods in San Mateo for 2021, ranked by their cost of living index. The cost of living index includes various items such as: goods and services, groceries, utilities, real estate and rental rates. For reference, the national average for cost of living is 100.