The cost of living in Castle Rock is 106, slightly above the national average of 100. That said, living in Castle Rock is still far below our competitors to our west (such as San Diego, Portland and Seattle) to the midwest (such as Chicago) and the east coast (such as Miami, New York and Washington, D.C.). Many would argue the cost of living in the Denver metro area is greatly outmeasured by the quality of living. The cost of living in Castle Rock is slightly lower than our Douglas County counterparts Lone Tree (108), Parker (107.6) and Highlands Ranch (107.6).