Complementing the current paradigm change from QoS to QoE, we address fundamental QoE charging issues for Internet services from an end user perspective. Here, key issues arise from gaps of different information contexts involved, which have to be managed when introducing a QoE product. Hence, this paper analyzes the double role of prices for quality perception as well as the impact of QoE on user demand with the help of a fixed point model. Our model is consistent with real-world user behavior that we have observed during comprehensive user trials on quality perception for Video on Demand services. Based on these results, we propose a simple approach for convergence-based user classification, and discuss the complementarity of Willingness-to-Pay vs. subjective quality perception in service purchasing situations.