Have you ever delivered a proposal (not a bid) where you “just knew” you were going to get the account? Your presentation went excellent, all the buying signs from the prospect were there, and you left confident you would be selected to perform the service. But then they proceed to explain that you came in second to another company.
Webster’s dictionary defines consultant as "a person that provides professional and/or expert advice." Therefore, if you use the services of a lawyer or a CPA, you are already using consultants. Each, of course, provide cost-effective service that the individual entrepreneur growing a small company is not likely to be able to provide internally.