The typical asking rate per listing is in the $30's per square foot per year. The Sebastopol region is seeing a an increase in rates. In the last 3 months, the median rate rose $36 per sqft per year.
Compared to the rest of the Bay Area market, the Sebastopol region has less expensive rates, so you should have no trouble finding a great deal in this depreciated submarket.
In the last 90 days, 1 listings have been made available, which means listings most likley are leasing quickly. You'll want to be prepared to tour spaces as quick as possible. About 800% of the listings in the Sebastopol 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 on the market, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,900 sqft. Most properties in this area are approximately 2 floors. Most buildings in this area were built in 1991 and are Class B.