Most listings are in the $40's per square foot per year. The Danville region is experiencing a a rise in rates. In the last 3 months, the median rate rose $45 per sqft per year.
Compared to the rest of the East Bay market, the Danville submarket has smaller rates, so you should have no trouble finding a great deal in this discounted submarket.
In the last 90 days, 5 listings have been posted online, which means spaces most likley are leasing quickly. You'll want to be prepared to make an offer immediately. About 100% of the available leases in the Danville are subleases, so you might be able to sign a shorter term by taking over a previous lease. 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 1,140 sqft. Most properties in this market are around 2 stories. Most buildings in this market were built in 1982 and are Class B.