There are usually two ways in which investigators cost for running surveillance on the perhaps unfaithful wife or husband (referred to as the Person of Interest or POI in investigator jargon): hourly costs and retainers. This is often also occasionally accompanied by incidental expenses distinctive to the case like travel. https://elliotapblw.blogtov.com/11993584/detailed-notes-on-cost-for-private-investigator-to-follow-my-wife