The fee required by RCW 33.08.110 to be submitted in connection with an application to establish a branch office of an association shall be five hundred dollars. In the event the actual costs of the investigation with respect to a particular application are less than the amount of the fee, such difference between the fee and the actual cost submitted shall be refunded, provided that in no event shall more than three hundred fifty dollars be refunded. For the purposes of this section, actual costs shall include travel and per diem expenses paid to division personnel in connection with the investigation.