(a) Procurements and contracts by and for the following state governmental entities shall be exempt from the operation of this chapter:

(1) The legislative branch;

(2) The judicial branch;

(3) The board of trustees of the University of Tennessee system, the Tennessee board of regents system, and the state university boards;

(4) Contracts advertised and awarded by the state building commission pursuant to § 4-15-102. If there is a question whether a contract or procurement requires state building commission or central procurement office approval, the chief procurement officer and the state architect shall determine in writing the procurement method or the contract form that is in the best interest of the state. Any such agreement reached by the chief procurement officer and the state architect shall be subject to the approval of the comptroller of the treasury;

(5) Construction and engineering contracts entered into by the department of transportation pursuant to title 54, chapter 5;

(6) Contracts for procurement of services in connection with the issue, sale, purchase, and delivery of bonds, notes and other debt obligations or the administration, safekeeping, and payment after delivery of such debt obligations by the state or any of its agencies;

(7) Contracts for appraisal, relocation or acquisition services related to the acquisition of land that are entered into by the department of transportation pursuant to title 54, chapter 5; and

(8) Administrative contracts for specific service signs pursuant to title 54, chapter 5, part 11, shall be awarded to the vendor who offers the lowest responsible response. The basis of all responses shall be the least cost to the retail user of the signs. All administrative contracts shall be awarded on an objective, competitive basis pursuant to rules and regulations promulgated by the department of transportation.

(b) Notwithstanding subsection (a), any or all state entities exempt from the requirements of this part, as well as any private nonprofit institution of higher education chartered in this state, are authorized to procure goods or services under this chapter through the central procurement office.