Most listings are in the $40's per square foot per year. The East Bay submarket is going through a an increase in rates. In the last 3 months, the median rate increased $7 per sqft per year. That's a 18% rise in rent.
Compared to the rest of the East Bay market, the East Bay region has less expensive rates, so you should have no trouble finding a great deal in this undervalued submarket.
In the last 90 days, 721 listings have been made available, so you'll want to check back regularly for new listings. About 5% of the available space in the East Bay are subleases, so you will probably have to focus your search on direct office leases. 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 2,380 sqft. Most properties in this market are around 2 floors. Most buildings in this area were built in 1983 and are Class B.