It depends on the situation, is it a domestic small garden, large farm or golf course. Some pesters charge a fixed price, per mole or per trap, I myself charge a fixed price after a comprehensive survey and take into account the time I am going to spend there each day, fuel and how many visits its going to take. It all depends on what your time and skill is worth and how busy you are, its trial and error to start but dont sell yourself short just to get the work.