Yeah, I wasn't thinking about it being cheap or inexpensive.
(Though lorewise it could be relatively tech-cheap.)
What I would really like if it was a form of active missile defense. High speed and acceleration, but incredibly low range, so you could only launch it at battleships that are almost on top of your base. It would introduce a little skill to it.
Alternatively, it could just do serious damage to a battleship, so you'd need a few of them to actually down it.
Either way, it should do enough damage to destroy the battleship instead of just crash landing it.