I would think a burst of 20mm cannon fire would work at 0.01% of the cost.
Wouldn’t work for the high altitude balloons. 1) No way to get the gun there and stabilized. Too much relative airspeed between fighter and balloon. Aircraft must fly at high true airspeed to maintain altitude when high.
2) Wouldn’t work anyway. High altitude balloons have sustained a large number of punctures and even missile hits to the envelope without much of a descent. Almost no pressure differential between inside and outside the envelope so gas mostly stays put.