1. A computer-implemented method for composite pricing, comprising: establishing a plurality of elementary pricing models and one or more pricing parameters, at least one of the plurality of elementary pricing models including a value-based pricing model, which sets a price as a function of an expected value to be derived to a customer; automatically selecting by a processor two or more elementary pricing models, including a variable fee and a fixed fee, from the plurality of elementary pricing models based on user selected solution; automatically estimating whether to use said one or more pricing parameters; constructing by a processor a composite pricing model based on said two or more elementary pricing models and said one or more pricing parameters; optimizing the composite pricing model to minimize risk and maximize one or more selected criteria, the optimizing including determining proportions of said selected two or more elementary pricing models to be utilized in the composite pricing model; and generating a price utilizing the optimized composite pricing model, wherein a two stage pricing model solves a pricing problem reversely, a first stage determining a proportion of the variable fee including at least a performance fee, a benefit fee and a usage fee that minimizes total risk of the variable fee, a second stage determining a proportion of the fixed fee and the variable fee based on customers' satisfaction and providers' risk affordance, the total risk of the variable fee determined as min ⁡ ( p m p ) 2 ⁢ σ p 2 + ( b m b ) 2 ⁢ σ b 2 + ( u m u ) 2 ⁢ σ u 2 s. t. ⁢ p + b + u = 1 wherein, a proportion of the performance fee, benefit fee and usage fee is p, b, u respectively, and a mean and a standard deviation of data of the performance fee, benefit fee and usage fee is m p , m b , m u and σ p , σ b , σ u , respectively.