In United States v. Jones, five Supreme Court Justices wrote that government surveillance of one’s public movements for twenty-eight days using a GPS device violated a reasonable expectation of privacy and constituted a Fourth Amendment search. Unfortunately, they didn’t provide a clear and administrable rule that could be applied in other government surveillance cases. In this Essay, Kevin Bankston and Ashkan Soltani draw together threads from the Jones concurrences and existing legal scholarship and combine them with data about the costs of different location tracking techniques to articulate a cost-based conception of the expectation of privacy that both supports and is supported by the concurring opinions in Jones.