Any minor repair, involving an alteration of buildings and not exceeding $5,000 in cost, may be progressed without special order and without public bidding. Any reliable person not in the employ of the State agency, or firm qualified to do the work, may be employed under informal agreement and the same may be engaged to furnish both materials and labor. In such case, the regular purchase order procedure shall be followed and the regular vouchers submitted to this office for audit and payment. Work in excess of $5,000 up to an amount of $50,000 may be done through special order (short form contracts). No such project exceeding $50,000 shall be undertaken through the special order system.