FB buying/selling groups (particularly for housing) are quite common I'd say. In my experience, you will generally find them categorized as part of a college or

FB buying/selling groups (particularly for housing) are quite common I'd say. In my experience, you will generally find them categorized as part of a college or university (e.g. "San Jose State University (SJSU) Housing"), but a quick search for "Bay Area housing" also results in numerous such groups.