Public Works Contracting. Learn how the County buys products and services.Search contracts, find open solicitations on BuyNet. The following forms and requirements are provided so that vendors can easily obtain necessary information for bidding and awards. Register with BuyNet today and begin receiving notice of business opportunities from the County of San Diego. All you need to do is complete the online registration form and submit your bid. You will automatically be included in our vendor database. Eligible employees will submit their bid using the bid form provided with the posting of the job advertisement. New Vendor Form For Payment.