It is unlawful for a person or business to be retained or for a business to retain a person or business to solicit or secure a contract upon an agreement or understanding that the compensation is contingent upon the award of the contract, except for retention of bona fide employees or bona fide established commercial selling agencies for the purpose of securing business and persons or businesses employed by a local public body which are providing professional services to the local public body in anticipation of the receipt of federal or state grants or loans.