The county commission may appoint, promote, demote, and remove employees of the planning commission as it deems necessary. The county commission may also contract with county or city planners, engineers, architects, and other consultants and with any local, state, or federal agency for such services as the planning commission may require. The county commission may cooperate with and accept funds from federal, state, and local public or public semi agencies, private individuals or corporations, and may expend such funds and carry out such cooperative undertakings and contracts for necessary planning studies. The expenditures of the planning commission, exclusive of gifts, grants, or contract receipts, shall be within the amounts appropriated for the purposes of the planning commission by the county commission.