The excavation calculators include various calculators that help estimate the cost and the amount of materials you will have to deal with.
It is pretty hard to come up with an upfront price for excavating. The amount of time it takes to excavate a hole for a basement will have a lot to do with the operator's skills, and of-course, the great unknown of what is in the ground of the excavation location.
More than likely, the excavator will charge an hourly rate.