I am totally on board with individual vehicles as a last-mile solution, and self driving vehicles are a great option for that, but expecting them to provide the entire trip puts us right back in the situation we find ourselves now with human driven cars.
Unless we are going to shrink these vehicles down to the size of a bicycle, mass transit for the bulk of the route will always win out in terms of efficiency.
You can buy similar commercial chassis for about one fifth of that. Control systems depending on whether they are intended for autonomous operation or remote control would be maybe 5-20k on top of that. I have no idea what the mounted weaponry in worth.
The real question is whether they are paying inflated military prices as is typical with US equipment, or building them in house at cost.