If you have the money for that, you either build a cruise missile that flies very close to the terrain, or an ICBM that rushes down from space at a speed that makes if very hard to intercept.
If you build your rockets from water pipes, nitrate fertilizer, sugar, and a blob of high explosive, as most Palestinian rockets are [1], you don't invest into a flight control system at all, only into the aiming system and the efficiency of mass production and mass launch.
If you build your rockets from water pipes, nitrate fertilizer, sugar, and a blob of high explosive, as most Palestinian rockets are [1], you don't invest into a flight control system at all, only into the aiming system and the efficiency of mass production and mass launch.
[1]: https://en.wikipedia.org/wiki/Qassam_rocket#Design