I have found that the best way to price a job is to a calculate all your costs which include your time, mileage, ect. To do this you need to know how long you plan to trap there and how many trips you will make to the job. Say your market will bear 500$ for the job. I would charge 250$ up front and then the other half when you finish. I am confident I will catch and know what conditions allow for the best trapping time. I never set a start and end date. I tell them I will trap for ten days. I can usually kill them all in that time period on 1-5 acres. I set up heavy. Maybe 20 traps on 2-3 acres. If not then I will return and kill them on a per head basis. Say 60$. If they want me to trap longer than 10 days.
Without looking at the job, knowing your skills, or how many traps you have, how long it takes you to set them, or how much you need to make your time worth, it is hard to tell you an exact price.
Most important fact is that you will learn from this job how much, and how long it takes to do it. Then when you bid your next job you will have a better idea what to charge. It was that way for me any how. I asked the same questions you did, but I had to figure it out myself. Its all about being an entreaupenur. Sell yourself and your service. Your a professional.To do the job I would charge no less than 300-500$ for 10 days of trapping with two trap checks included.