California Code, Public Utilities Code - PUC § 60040

(a) Contracts for the purchase of services, supplies, equipment, and materials in excess of ten thousand dollars ($10,000) shall be awarded to the lowest responsible bidder after competitive bidding, except in an emergency declared by the district or by an executive committee to which the district has delegated responsibility to make that declaration.

(b) If, after rejecting bids received under subdivision (a), the district determines and declares that, in its opinion, the services, supplies, equipment, or materials may be purchased at a lower price on the open market, the district may proceed to purchase these services, supplies, equipment, or materials in the open market without further observance of the provisions regarding contracts, bids, or advertisements.

(c) Notwithstanding subdivision (a), the district shall comply with Federal Transit Administration Circular 4220.1 (d), as amended, relative to third-party contracting.