In this letter, we develop a robust and scalable algorithm to cope with the sensor placement problem for target location under constraints of the cost limitation and the complete coverage. The problem is NP-complete for arbitrary sensor fields. The grid-based placement scenario is adopted and the sensor placement problem formulated as a combinatorial optimization problem for minimizing the maximum distance error in a sensor field under the constraints. The proposed algorithm is based on the simulated annealing approach. The experimental results reveal that, for small sensor fields, the algorithm can find the optimal sensor placement under,the minimum cost limitation. Moreover, it can also find a placement with minimum distance error for large sensor fields under the cost limitation.