How much does it cost to deal with there's a big branch hanging in the tree?

Priced by access to the limb rather than by the limb's size — a hanger sixty feet up over a roofline means a bucket truck or a climber setting lines above it, and that dominates the bill regardless of whether the branch weighs eighty pounds or four hundred. Because the actual cut takes minutes, after-hours mobilization is usually the largest line item. Worth asking them to clear other deadwood in the same canopy while they are already tied in, since you are paying for the setup either way.