Co-ops are all over - What is a housing cooperative? A housing cooperative is formed when people join with each other on a democratic basis to own or control the housing and/or related community facilities in which they live. Usually they do this by forming a not-for-profit cooperative corporation. Each month they simply pay an amount that covers their share of the operating expenses of their cooperative corporation. Personal income tax deductions, lower turnover rates, lower real estate tax assessments (in some local areas), controlled maintenance costs, and resident participation and control are some of the benefits of choosing cooperative homeownership.
Specifically in Santa Clara County - you will usually see if they are (or aren't) on the MLS. My guess, less than 5% are co-ops. Hope this helps.