No expenditures shall be made, or liabilities incurred, or warrants issued, in excess of the budget estimates as finally determined by the board of supervisors, or as thereafter revised under the provisions of this chapter. The board of supervisors shall not approve any claim, and the clerk shall not issue any warrant for any expenditures in excess of the budget estimates thus made and approved by the board of supervisors, or as thereafter revised under the provisions of this chapter, except upon the order of a court of competent jurisdiction, or for an emergency as hereinafter provided. Any violation of the provisions of this section shall make the members of the board of supervisors voting for same, and the surety upon their official bonds, liable for the full amount of the claim allowed, the contract entered into, or the public work provided for, and the State Auditor, as the head of the State Department of Audit, shall be authorized to sue for the recovery of the sum or sums so voted. Provided, however, that the term “budget estimates” for purposes of personal liability of the members of the board of supervisors under this section shall not include any unfunded liability for county employee retirement or pension funds. Nothing in this section shall diminish any responsibility of the members of the board of supervisors to fund any employee retirement or pension plans, or any liability as a result of any failure to fund such plans as otherwise required by law.