Sidewinder missiles are more then a quarter million a pop.
The Upwinder ballonic missile is a relative steal at just a few grand, including a proportional guidance system and directional vanes that allow for simplified target vectoring..
The guidance system itself with spinning mirror sits on the
top of the balloon on a lightweight carbon fiber scaffolding, that also holds a lightweight vanes. This is counterweighted.
Payload can either be four two to three meter spears similar to fishing poles with sharpened spike, or an lightweight fragmentation warhead. Hooked spikes also can be used, attached to stowed parachutes, for retrieval purposes.
As enemy floating spy vehicles or 99 red balloons float gracefully from west coast to east, freight trucks loaded with bundles of ballonic missiles drive just in front of them, releasing a cheap barrage of floating hell.