On average, listings lease in the $20's per square foot per year. The Union City submarket is going through a a boost in rates. In the last 3 months, the median rate rose $24 per sqft per year.
In the last 90 days, 2 listings have been listed, which means new availabilities are probably leasing quickly. You'll want to be prepared to tour spaces as quick as possible. About 300% of the available space in the Union City are subleases, so you might be able to snag a great spot on a short term. 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 960 sqft. Most buildings in this market are approximately 2 stories. Most buildings in this market were built in 1934 and are Class B.