This paper describes a control mechanism for a future Internet. It is an economic mechanism that enables users to choose different pairs of price/QoS priority levels for network services at the user time scale. User time scale means that prices vary at a rate suitable for human beings to respond to those price changes. The changes might happen on an hourly, daily, or weekly basis. We believe that such an economic control mechanism at medium time scale, which is coupled with a technical rate control mechanism at a short time scale, is a simple and cost-reducing system that can provide quality of service to end-users. We show that the approach proposed enables network service providers to react to network congestion appropriately and provides end-users with high flexibility in service selection. After discussing different Internet pricing principles, we describe the market-managed test network, the QoS pricing and charging software for network services, and the experiments run on a DiffS...