Most listings are in the $10's per square foot per year. The Manchester submarket is going through a decline in rates. In the last 3 months, the median rate fell $9 per sqft per year. That's a 32% decline in rent.
Compared to the rest of the Greater Boston market, the Manchester region has smaller rates, so you should have no trouble finding a great deal in this discounted submarket.
In the last 90 days, 19 listings have been made available, which means leases 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 posted, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,620 sqft. Most buildings in this market are close to 2 floors. Most buildings in this area were built in 1913 and are Class Class B.