Should the director, or designee, determine that it is necessary or desirable to have the work performed in phases, it will not be necessary to negotiate the total contract price in the initial instance, provided that the director, or designee, shall have determined that the firm is best qualified to perform the work at reasonable cost, and the contract contains provisions that the state, at its option, may utilize the firm for other phases and the firm will accept a fair and reasonable price for subsequent phases to be later negotiated, mutually-agreed upon and reflected in a subsequent written instrument. The procedure with regard to estimates and negotiation shall otherwise be applicable.