Most listings are in the $10's per square foot per year. The Belleville submarket is seeing a decrease in rates. In the last 3 months, the median rate fell $3 per sqft per year. That's a 16% decrease in rent.
In the last 90 days, 6 listings have been made available, which means spaces most likley are going fast. You'll want to be prepared to make an offer immediately. 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 1,080 sqft. Most properties in this market are approximately 2 stories. Most buildings in this region were built in 1951 and are Class B.