Although you may reserve and hire a DJ, Event Designer, and/or Coordinator for 4 to 8 hours for your event you actually get several more hours of service for your money.  In fact, with DJs you may receive 10-35 hours of consultations, music purchasing, editing, and other preparation work; while Event Designers and/or Coordinators can spend anywhere from 100 hours to well over 250 hours on consulting, designing, decorating, phone calls, travel, negotiations, and/or other types of planning for your event.  Don't forget, all will probably also spend time conducting or coordinating some form of delivery, set-up, brake-down, and (in the case of many event coordinators) next day returns of rental items too.  For most clients buying "time" is money well spent.