Sec. 7. Except for persons the authority considers necessary to prepare complete plans and specifications necessary for bidding for construction, the authority may not enter into:
(1) a contract for the performance of work, other than a contract of employment with a professional person or a commission employee; or
(2) a contract for the purchase or sale of materials or supplies;
without complying with IC 4-13-2 and the rules and procedures of the department of administration.