One breeder from San Diego (Rancho Penasquitos) retired from their day jobs and moved to Texas; Bob & Terry Reed of Illusion Basenjis. Another San Diego breeder (Spring Valley) passed away almost 2 years ago; Doug Joy of Basenjis of Dune. Not all reputable breeders are visible on the BCOA website. Some don't want their kennels named because they do not breed very often. You should contact the breeder liaison via email for more breeders in California and other nearby states.
The local breed club for southern California is The South Coast Basenji Fanciers. They can help you find a local breeder. The quickest way to get in touch with them if through their Facebook page: https://www.facebook.com/SoCalBasenjiFanciers
Northern California also has a breed club that you can contact, BCONC. Their Facebook page is: https://www.facebook.com/norcalbasenjis