Most listings are in the $10's per square foot per year. The Mendocino region is going through a a boost in rates. In the last 3 months, the median rate increased $17 per sqft per year. That's a Inf% rise in rent.
In the last 90 days, 4 listings have been made available, 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 available, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 740 sqft. Most properties in this region are approximately 1 stories.