With the rapid development of wireless power transfer technology, Wireless Rechargeable Sensor Networks (WRSNs) can be realized by deploying static or mobile chargers to replenish power for rechargeable sensor nodes. For WRSNs, a novel device-initiated charging service model was proposed recently, which regards mobile cooperative charging as a business service. Based on this model, most of the existing works mainly focused on charging cost minimization problem, however, they all ignored budget constraints and limitation on number of charging locations, which are both significant factors in real applications. In this paper, we adopt such device-initiated charging service model and study charging utility maximization problem in budget-constrained WRSNs with limited charging locations. To this end, we first prove its NP-hardness, and then propose a polynomial-time algorithm for single-charging-station case, which can achieve a constant-factor approximation ratio. Further, we solve the target problem with multiple-charging-station case by devising an efficient greedy-based solution. Finally, the extensive simulation results reveal the advantages of our proposed solutions over the other baselines.