The $2,400 Leakage. How crowdsourced, GPS-verified pricing networks reclaim opaque brick-and-mortar retail margins for the American household.

Physical brick-and-mortar retail accounts for the large majority of essential household expenditures, yet remains one of the most opaque pricing environments in the modern economy. Consumers face significant geographic price dispersion, dynamic chain-level pricing, and marked-up convenience delivery layers that can inflate identical baskets by double-digit percentages depending on the shopper. This paper introduces the Geospatial Lattice, a crowdsourced, GPS-verified physical price index built from real in-store receipt data. By leveraging an Asymmetric Inference Model for semantic inventory normalization and the Sovereign Protocol for privacy-first, opt-in participation, CartLens establishes a localized price discovery network. We define the Leakage Protocol and the Efficiency Ratio as a mathematical model for measuring household retail spend performance. Simulation results based on the network's contributor-density model demonstrate that once a regional density of 20 active stores is established, local price discovery accuracy plateaus near 96.5% with a latency of under three hours. We conclude that crowdsourced price discovery can help the average American household reclaim on the order of $2,400 in annual leakage.