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 $24 per sqft per year.
In the last 90 days, 2 listings have been posted online, which means new listings might be leasing quickly. You'll want to be prepared to make an offer immediately. About 250% of the listings in the Union City are subleases, so you might be able to find a shorter term or below market rent. 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 close to 2 stories. Most buildings in this market were built in 1934 and are Class B.