You are effectively asking a question that cannot be answered with any high level of accuracy, as it would strongly suggest that a component has become defective, and as the offending part can range from being either a capacitor / resistor or IC a certain "on the spot" diagnosis has to be carried out to determine which, so its quite impossible to state what kind of cost would be involved, as although the components are not really expensive the time taken to find whatever can mount up, this being far in excess of component costs. It could of course also be a dry joint that is responsible, and these are not always the easiest or quickest thing to find.