Current mobile applications oftentimes require power-consuming localization services. In this paper, we outline the co-localization approach, where nodes share their location with peers, enabling a reduction in the costs of localization when a precise location fix is desired. While several works in this domain compare the accuracy of localization techniques in cooperative scenarios, we focus our evaluation on the power consumption and accuracy that can be achieved. We present a first model and evaluation using statistics and traces derived from two human mobility models. We find that for 15 min intervals of location requests, a cooperative localization approach can reduce the costs associated with localization if half of the nodal peer encounters are with location-sharing nodes and GPS is usable about half the time.