贱买贵卖

Explanation: Buy low, sell high. 　　Source: Han Ban "Han Emperor Jing Ji" by the prison officials came, and to avoid eating, weight; subject property, buy low and sell, on the light. " 　　Examples: If the brokers, the heart will be cheap, the ~, selfish. ★ Ming Shen by the first "triple farewell note" Thesaurus:  Convergence expensive cheap, Low progress overtop, Cheap grabbing your hair, buy Dump costly