The typical asking rate per listing is in the $30's per square foot per year. The San Anselmo region is seeing a decline in rates. In the last 3 months, the median rate decreased $19 per sqft per year. That's a 39% decrease in rent.
Compared to the rest of the Bay Area market, the San Anselmo region has smaller rates, so you should have no trouble finding a great deal in this discounted region.
In the last 90 days, 3 listings have come on the market, which means spaces might be going fast. You'll want to be prepared to tour spaces as quick as possible. There aren't many listings below 2,000 square feet posted, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,400 sqft. Most buildings in this market were built in 1965 and are Class B.