Last one I did, I just charged my hourly rate plus the rental cost of the machine. The majority of your time is going to be spent removing the sod after it's cut. Cutting it with the sod cutter is cake and shouldn't take that long.
Fortunately, one of her neighbor's up the street needed the sod for his yard so I told him I'd give it to him for free if he helped me load it on the trailer and unload it at his house up the street. I didn't have anything to dispose of thankfully.