Happy with it
When the estimate for the hugely expensive addition came in, I was content with it, because it wasn't as high as I feared it would be. I decided that the price was right.
So now, when I see that they used brand new lumber -- that we paid for -- to build forms for the foundation, and stacked it up neatly after removing the forms, I tell myself not to wonder about how many dollars they'll earn back when they resell that lumber. And when I see a guy using our hose to meticulously clean the metal stakes that held the forms in place, I tell myself not to fret that we're paying for his labor on behalf of the company.
An addition is a luxury expenditure, like buying a car, only much worse. Yes, there is going to be same fat they slice off of you, but if you were happy with the total sticker price, stay happy. Don't fret.