The typical asking rate per listing is in the $0's per square foot per year. The Sonoma submarket is going through a decline in rates. In the last 3 months, the median rate fell $50 per sqft per year. That's a 100% decline in rent.
In the last 90 days, 5 listings have been posted online, which means leases are probably leasing quickly. You'll want to be prepared to make an offer immediately. There aren't many listings below 2,000 square feet on the market, so finding a space for a small business might be tough.
Even though the median size is 4,640 sqft, there are still 0 new listings below 2,000 sqft. Most properties in this market are around 2 floors. Most buildings in this area were built in 1978 and are Class C.