With the rise of cheap small-cells in wireless cellular networks, there are new opportunities for third party providers to service local regions via sharing arrangements with traditional operators. These arrangements are highly desirable for large facilities - such as stadiums, universities, and mines - as they already need to cover property costs, and often have fiber backhaul and efficient power infrastructure. In this paper, we propose a new network sharing arrangement between large facilities and traditional operators, called a facility micronetwork. Our facility micronetwork concept consists of two aspects: leasing of core network access from traditional operators; and service agreements with users. Importantly, our incorporation of a user service agreement into the arrangement means that resource allocation must account for financial as well as physical resource constraints. We evaluate the facility micronetwork concept by analyzing the moments of the stochastic revenue process from serviced users. Using our analysis, we demonstrate the impact on the profitability of facility micronetworks based on physical layer - modeled via stochastic geometry - and financial parameters.