Smartphones nowadays are regarded as outstanding carriers for mobile sensing crowdsourcing due to their pervasiveness and excellent sensing capability. However, how to properly stimulate phone users to participate remains a question. In this paper, we study incentive mechanisms in which each user bids her cost for participating and the job owners pay the users she selected for sensing. We consider a bidding style that is quite common in practical mobile phone sensing applications but has not been studied in existing work on mobile phone sensing mechanism design. We show how the job owner could properly select users and reduce her total payment at the same time even when users could submit fake costs.