People seem to forget that a unit's flying hours are "paid for" at the beginning of the fiscal year. The unit that performed the flyby was going to fly those hours no matter what, regardless of if it was around the flagpole and the home 'drome or if it was over the top of a closed stadium.
Certainly there was no extra taxpayer funds spent specifically on this flyby.
Besides, the "price" quoted was simply a critic's best guess at the cost.