On average, listings lease in the $10's per square foot per year. The Willimantic region is seeing a a rise in rates. In the last 3 months, the median rate increased $16 per sqft per year.
Compared to the rest of the Greater Boston market, the Willimantic submarket has smaller rates, so you should have no trouble finding a great deal in this depreciated region.
In the last 90 days, 2 listings have been made available, which means new availabilities are probably going fast. You'll want to be prepared to tour spaces as quick as possible. About 150% of the available space in the Willimantic 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 850 sqft. Most buildings in this market are close to 2 floors. Most buildings in this market were built in 1925 and are Class C.