Private detectives make a median annual wage of between $40,000-$50,000 (source). The average rate for a private detective is $50 an hour but the really good ones in Hollywood make ten times that figure. Planting evidence costs extra (note: please do not plant any evidence, anywhere). To calculate a quote for a case, a private detective will estimate how many hours they need to work. Once they figure out the hours, they give the client a quote before investigating. The client must review cases that run longer than the amount estimated for the investigation.