My guess is that the price out of the factory for ESP modules is not much more than a few pounds. Presumably there is no real competition for replacement units because of trade restrictions and practice. No doubt otherwise perfectly serviceable vehicles are wasted due to this. It is ironic that the government encourages or sometimes enforces safety systems which the manufacturer uses, when they fail, as a means to firstly gouge customers when their vehicles are young enough and ensure premature scrapping later (when the car's value is low making repair uneconomic), which is an unnecessary waste of the worlds limited resources. But that’s life.