On average, listings lease in the $40's per square foot per year. The Blackhawk submarket is going through a a boost in rates. In the last 3 months, the median rate rose $48 per sqft per year.
Compared to the rest of the East Bay market, the Blackhawk submarket has greater rates, and you'll need to make a great offer to be in this hot region.
In the last 90 days, 1 listings have been made available, which means spaces most likley are going fast. You'll want to be prepared to make an offer immediately. 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 250 sqft. Most properties in this region are close to 2 floors. Most buildings in this area were built in 1989 and are Class A.