In my area, if someone goes missing, there is a preliminary investigation by the police. If they choose to call SAR volunteer groups, we will always gather our people and our gear and just go.

There is no charge, costs are assumed by police departments (salaries) and the SAR teams themselves.

They usually don't cost much, since everyone already has their personal gear, etc. It may cost a few hours of your time, but that's usually it.

For the record, most of the searches I have been involved in last about 12 hours from start to finish. In somes cases the lost person is found in the very early stages of the search. In the other cases, the persons were simply never found.