Most military grade drones cost $10k or more and they can only be used once.

An optimized quadruped could probably be built for the same price and have an integrated 60mm mortar instead. The front legs act as the bipod and the rear legs would be designed to dig into the ground for stabilization. The only problem here is reloading the mortar, which could be done using a revolver style magazine. That's 5 shots per robot vs 1 per drone.