This letter proposes a novel and open method for pricing substitute elastic services in a streaming content delivery scenario when their Grade of Service (GoS) is guaranteed. The method forces each Service Provider (SP) to calculate the rate for each substitute service that guarantees the GoS. The price of each service is obtained according to the maximization of a chosen revenue function and the estimation of its demand function. This letter illustrates the method calculating the price of two substitute services with a selected exponential demand function, where the assignation of the prices depend on the maximization of a selected revenue function.