While health care and general goods and services tend to run a little higher than the national average, the cost of living in Phoenix is still generally low. The rating on the US cost of living index is 95, just below the national average of 100. A gallon of gas in Phoenix is 10 percent lower than the national average. Average rent for an apartment is $1,027 (national average: $799) and the median home value is just over $258,720 (..