Flyovers don't cost extra money as long as it's done as part of training, at least down here in the training command. Rarely do we launch a flight that does include getting the "X" so taking them away, at least from our perspective, doesn't make or break anything.
With regards to the flight demo teams, it obviously cost money to maintain, practice, fly, etc but they do give back in a way. Pensacola stated they bring in $2.5 million in one day during the July Pensacola Beach Airshow. Good for the local economy.