Most listings are in the $30's per square foot per year. The Concord submarket is going through a a boost in rates. In the last 3 months, the median rate rose $2 per sqft per year. That's a 4% rise in rent.
Compared to the rest of the East Bay market, the Concord region has more expensive rates, and you'll need to pay a premium to be in this hot region.
In the last 90 days, 33 listings have been made available, which means office spaces might be leasing quickly. You'll want to be prepared to make an offer immediately. About 9% of the listings in the Concord are subleases, so you will probably need to consider the implications of signing a direct lease with the building. 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 2,200 sqft. Most buildings in this market are close to 2 stories. Most buildings in this area were built in 1984 and are Class A.