When labor is a major part of a purchase order or contract (exclusive of contracts for construction and repair work which are covered in Part 4 of this Title) such purchase orders or contracts do not require approval of the Office of General Services and shall therefore be forwarded directly to the Comptroller. Competition is required on all such transactions which lend themselves to competition, and prior approval of the Comptroller is also required when the amount thereof exceeds $1,000. When it can predetermined from past experience or knowledge of anticipated cost that charges in the aggregate for a certain service will exceed $1,000 in a given fiscal year, such transactions also shall be subject to contract, competitive bid requirements and prior approval of the Comptroller. It is an administrative agency responsibility to obtain competitive quotations or bids on transactions of $1,000 or less when it is deemed in the best interest of the State to do so. However, prior approval of the Comptroller is not required.