Cal. Pub. Cont. Code § 20207.7

Unless the amount involved in the purchase at any one time of any articles for which no contract has been entered into exceeds ten thousand dollars ($10,000), the board may purchase the articles without the necessity of advertising or letting contracts. Where the cost of any articles for which no contract has been entered into exceeds ten thousand dollars ($10,000), the board shall advertise for sealed bids for furnishing the district the articles. In the matter of advertising, opening and accepting bids, and the letting of contracts, the board shall proceed in all respects in the manner and form provided in the case of contracts for annual supplies.