A big part of modern guidance package cost is rejection of noise and countermeasures. This still requires an expensive sensor implementation even though a cheap camera would work well in ideal conditions.
Sure, but the classical rotary telescope setup shouldn't be a must for countermeasure resistance. A lot of targets like Russian cruise missiles for Ukrainian harassment don't integrate countermeasures yet. I don't think flares/distractions resistance justifies the cost difference between something like $49 and $490k per unit.