Funny, though tbh it seems like there are cheaper ways 
    to cause the US to spend gobs of cash.

My best understanding based on watching a lot of retired military personnel is that isolated incidents cost the US almost exactly zero additional dollars.

The way an Air Force base works is this: there is a budget. This covers the (considerable) costs of the base itself, the personnel, the equipment, and so on.

Active-duty fighter pilots must fly a certain number of hours per month to remain on active status. Just like any other demanding activity (sports, competitive gaming, whatever) their skills require constant maintenance. These flying hours are of course budgeted. (This will be true of literally any air force; it's not specifically a USAF thing)

Things like these incident responses, and even things like flyovers before sporting events, come out of those predetermined budgeted flying hours that they were going to fly anyway. So isolated incidents like these don't really increase USAF expenses in a meaningful way. Those $400K/ea missiles will presumably need to be replenished but this must be compared to the USAF's total budget of $180 billion.

To put any strain whatsoever on the US's capabilities our foes would need to start sending large amounts of drones: essentially, a saturation attack. More than we can comfortably respond to. Which is of course... extremely possible.

But as long as these remain isolated incidents we can surmise that our adversary's goal is not "cost the US a bunch of money."