On average, listings lease in the $20's per square foot per year. The Union City region is going through a a boost in rates. In the last 3 months, the median rate increased $4 per sqft per year. That's a 18% rise in rent.
In the last 90 days, 2 listings have come on the market, which means leases might be leasing quickly. You'll want to be prepared to tour spaces as quick as possible. 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 1,000 sqft. Most buildings in this market are around 2 floors. Most buildings in this area were built in 1934 and are Class B.