I think the answer is based on supply and demand. Like any service industry it's the standard of service that will create demand. The more demand the more 'exclusive' you become and the more you can charge. Provide a high quality service and word will spread creating more willing customers who will pay more for the privilege of the services you provide. One good review on TS sees a stampede of punters looking to enjoy a ladies company. Shortly after they complain her prices have increased...........supply and demand.