California Code, Public Contract Code - PCC § 20291

(a) The purchase of supplies, equipment, and materials, when the expenditure required exceeds fifty thousand dollars ($50,000), shall be by contract let, in the district's discretion, either to the lowest responsible bidder or to the responsible bidder that submits a proposal that provides the best value to the district. “Best value” means the overall combination of quality, price, and other elements of a proposal that, when considered together, provide the greatest overall benefit relative to the requirements described in the solicitation documents.

(b) The construction of facilities and works, when the expenditure required exceeds ten thousand dollars ($10,000), shall be by contract let to the lowest responsible bidder.

(c) The district shall obtain a minimum of three quotations, either written or oral, that permit the comparison of prices and terms in either of the following circumstances:

(d) Notice requesting bids shall be published at least once in a newspaper of general circulation, which publication shall be made at least 10 days before bids are received.

(e) The board may reject any and all bids and readvertise in its discretion.