Before any discussion with any firm concerning fees, the department may cause an estimate of the value of such services to be prepared. This estimate shall serve as a guide in determining fair and reasonable compensation for the services rendered. Such estimate shall be, and remain, confidential until award of contract or abandonment of any further procedure for the services to which it relates. At any time the department determines the estimates to be unrealistic because of rising costs, special conditions, or for other relevant considerations, the estimate may be reevaluated and modified if necessary.