Cal. Public Contract Code § 20131

Counties which employ purchasing agents may: (a) Authorize the agent to employ state-licensed independent contractors and purchase materials, furnishings, and supplies used in the construction or repair of public works estimated as costing not more than six thousand five hundred dollars ($6,500) without the formality of obtaining bids, letting contracts, preparing specifications, and the other things required by this article. (b) In counties containing a population of 500,000 or more, authorize the agent to purchase materials and supplies used in the construction or repair of public works estimated as costing not more than three thousand five hundred dollars ($3,500) without the formality of obtaining bids, letting contracts, preparing specifications, and the other things required by this article. (c) Authorize the agent to purchase or contract for medical or surgical equipment or supplies, or for professional services, for a county hospital without competitive bidding, so long as an appropriation for the costs of those purchases or contracts is included in the county budget. As used in this subdivision, “medical or surgical equipment or supplies” means only equipment or supplies commonly, necessarily, and directly used by or under the direction of a physician and surgeon in caring for or treating a patient in a hospital.