ISO 9001 consultants’ experience: ISO 9001 consultant fees are directly proportional to ISO consultants’ experience. ISO 9001 certification cost for experienced ISO 9001 consultants is usually higher than that for less-experienced ISO consultants. ISO 9001 certification cost also varies depending on the ISO 9001 consultant’s experience in ISO management system assessments, ISO 9001 audits, and ISO 9001 certification.