I don't know your charge, but Duane is right on! I feel that a fair price should not be lowered. The question is what is fair?
Your travel time is important as well as the type of course you are measuring. If it's an out and back then you could charge less. I generally charge about $50 per mile plus $100 for the paper work. In your case I would build in some charge for travel. Then another thing to consider is: do you have to design the course? If that's the case then that would involve some extra charge.
They could always do it themselves by following the guidelines, but if they choose to ask for an expert then present your charges and don't worry about their answer.