Ensuring Trust in One Time Exchanges: Solving the QoS Problem
  We describe a pricing structure for the provision of IT services that ensures trust without requiring repeated interactions between service providers and users. It does so by offering a pricing structure that elicits truthful reporting of quality of service (QoS) by providers while making them profitable. This mechanism also induces truth-telling on the part of users reserving the service. 
Bernardo A. Huberman, Fang Wu and Li Zhang