The typical asking rate per listing is in the $10's per square foot per year. The Riverbank region is going through a a boost in rates. In the last 3 months, the median rate increased $16 per sqft per year. That's a Inf% increase in rent.
In the last 90 days, 2 listings have been made available, which means leases most likley are 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.
The standard measurement for office space in this area is around 1,510 sqft. Most buildings in this market are around 0 floors. Most buildings in this region were built in 1955 and are Class A.