Notwithstanding any other provision of this part or any other law dealing with the subject matter contained in this Code section to the contrary, all construction or public works contracts, exceeding a total expenditure of $100,000.00, of any department, board, bureau, commission, office, or agency of the state government, except as provided in this Code section, shall be conducted and negotiated by the Department of Administrative Services in accordance with this part; provided, however, that any expenditure of less than $100,000.00 shall still be subject to review and approval by the Department of Administrative Services, which may approve noncompetitive expenditures of up to $100,000.00. All advertising costs incurred in connection with such contracts shall be borne by and paid from the funds appropriated to and available to the department, board, bureau, commission, office, or agency of the state government for which the contract is negotiated. The commissioner of administrative services is authorized and directed to promulgate such rules and regulations as shall carry out the additional duties and responsibilities placed upon the department by this Code section. Nothing contained in this Code section shall apply to or affect the Department of Transportation, the several public authorities of this state, including the Stone Mountain Memorial Association and the Board of Regents of the University System of Georgia, or the expenditure of money credited to the account of this state in the Unemployment Trust Fund by the secretary of the treasury of the United States pursuant to Section 903 of the Social Security Act and appropriated as provided in Code Section 34-8-85. No contract in existence on March 18, 1964, shall be affected by this Code section and such contract may continue to be utilized.