Depends on the job. I used to do some beaver jobs for so much a beaver. In some cases, I would do it for nothing if I were allowed exclusive access to the place for trapping other critters for that year and coming years. I was a water trapper and didn't get involved in much land trapping. I referred those jobs to another trapper.
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Also depends on the customer. If it looks like Grandma will go hungry paying to get 'possum out of her basement, we'll bargain. Collected two large Redwing crocks over the years doing that.
There are also the fun barters . . Culver's restaurant had a 'coon in the dumpster that didn't want to come out. Got an ice cream cake for my efforts. Barters for fishing gear, antique stuff, etc.
If it looks like the customer can afford a hundred bucks a beaver, that's what I'll charge. Unless I get bowhunting rights on good looking property or exclusive trapping rights. Then it's free depending on the situation.
The price goes to $200 a beaver if 1) the customer is an Ahole, or 2) decides after initial discussion and looking over the property they can do it themselves or find someone else. In which case I tell them don't bother calling me back. Mail me a money order for $500 as a down payment and then I'll get started.
Worst customers: farmers who tell you you've got sole trapping and/or bowhunting rights and you come back to a neighborhood. That and rich landowners who play games. Game players get told don't bother me again. And stick to it. That word gets around.
Always . . . get something before you get started.