The proliferation of electronic commerce has emphasized \nthe need for multiple qualities of service (QoS) that meet \nuser requirements for, e.g., best-eort services, transactional \nguarantees, prioritized services, and bandwidth reservations. \nWhen Internet users will be able to choose from a large selection \nof network services, an important question is whether \nthis \nexibility will be appreciated by the user and how much \nvalue is placed on network resources. This paper focuses on \nuser acceptance of dierent usage-based pricing models for \nnetwork services as well as on which users benet from dynamic \npricing. The analytic results presented here are based \non pricing experiments conducted within the INternet Demand \nEXperiment (INDEX). The pricing experiments comprise \nper-minute and byte-volume pricing. After describing \nthe experimental design and characterizing our subject pool \nusing demographic data, we analyze user demand for Internet \naccess by comparing the three experiments in terms of \ntraÆc generation, QoS selection, and expenditure. Finally, \nwe show which user groups will benet from such services.