An owner of an interest in a vacation time sharing plan may not be charged an up-front appraisal fee for the resale of his interest but may be charged only an up-front marketing fee or commission upon the resale of the interest in an amount stipulated by written agreement between the owner and his sales agent. A person violating the provisions of this section has committed an unfair trade practice pursuant to Section 39-5-20 and is subject to all penalties and remedies provided by law for this violation.