Most listings are in the $10's per square foot per year. The Brockton submarket is going through a a boost in rates. In the last 3 months, the median rate increased $20 per sqft per year.
Compared to the rest of the Greater Boston market, the Brockton submarket has lower rates, so you should have no trouble finding a great deal in this discounted region.
In the last 90 days, 16 listings have been listed, which means office spaces are probably going fast. You'll want to be prepared to make an offer immediately. 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 960 sqft. Most buildings in this area are close to 2 floors. Most buildings in this area were built in 1986 and are Class A.