Most listings are in the $10's per square foot per year. The Sebastopol region is experiencing a decline in rates. In the last 3 months, the median rate decreased $34 per sqft per year. That's a 72% decline in rent.
Compared to the rest of the Bay Area market, the Sebastopol region has lower rates, so you should have no trouble finding a great deal in this depreciated region.
In the last 90 days, 1 listings have been made available, which means listings are probably going fast. You'll want to be prepared to make an offer immediately. There aren't many listings below 2,000 square feet available, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,890 sqft. Most properties in this market are approximately 2 floors. Most buildings in this region were built in 1991 and are Class B.