What to charge to stack with bale wagon

I have a 1069 diesel bale wagon that we use to stack our hay. I have had some interest in being hired to custom stack. What is a good price. Some would be 2 miles from the barn, some is right beside the barn. The first person I've talked to mentioned maybe paying so much per bale, putting fuel in my machine and paying the operator a good operators wage for running the machine. Such as $15-20 an hour. What is everyone else getting in a situation like that?

What to charge to stack with bale wagon