Cal. Pub. Cont. Code § 20917

If, after rejecting bids received under Section 20916, the board determines and declares by a two-thirds vote of all of its members that, in its opinion, the equipment, supplies, or materials may be purchased at a lower price in the open market, the board may proceed to purchase the equipment, supplies, or materials in the open market without further observance of the provisions requiring contracts, bids, or advertisement.