On average, listings lease in the $40's per square foot per year. The San Anselmo region is experiencing a a boost in rates. In the last 3 months, the median rate increased $50 per sqft per year. That's a Inf% increase in rent.
Compared to the rest of the Bay Area market, the San Anselmo region has higher rates, and you'll have to negotiate above asking rent to be in this hot region.
In the last 90 days, 3 listings have been posted online, which means leases might be leasing quickly. You'll want to be prepared to tour spaces as quick as possible. About 33% of the office spaces in the San Anselmo are subleases, so you might be able to snag a great spot on a short term. 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 480 sqft. Most buildings in this area were built in 2004 and are Class B.