(a) Except as provided by Subchapter Q, unless the posting requirement in Subsection (b) is satisfied, a board may not let a contract that is:
(1) for more than $50,000; and
(2) for:
(A) the purchase of real property; or
(B) consulting or professional services.
(b) An announcement that a contract to which this section applies is being considered must be posted in a prominent place in the principal office of the authority for at least two weeks before the date the contract is awarded.
(c) This section does not apply to a contract that must be awarded through competitive bidding or for the purchase of an existing transit system.