costs. I get we all have different insurance, but what they heck man you can't ask people to pay a specific sum...only later and add on 33% because your staff didn't know what to charge the first time.
If your staff's estimate is over 15% off, they have not charged 'in good faith.' They simply have not done a good job.
In the business world, this doesn't fly. Come at me, I'm ready.