If, in the discretion of the board, it is advisable to offer to pay a commission to a licensed real estate broker who is instrumental in obtaining any proposal, the commission shall be specified in the resolution. No commission shall be paid unless there is contained in or with the sealed proposal that is finally accepted the name of the licensed real estate broker to whom it is to be paid, and the amount or rate thereof. Any
commission shall, however, be paid only out of money received by the board from the sale or rental of the real property.