The members of the committee are entitled to receive the per diem, mileage, and subsistence as is allowed by law for members of boards, committees, and commissions when engaged in the exercise of their duties as members of the committee. These expenses must be paid from approved accounts of their respective appointing authority. All other costs and expenses of the committee must be paid in equal proportion by the Senate, the House of Representatives, and the Office of the Governor, but only after the expenditures have been approved in advance by the President of the Senate, the Speaker of the House, and the Governor.