On average, listings lease in the $20's per square foot per year. The Nashua region is going through a an increase in rates. In the last 3 months, the median rate went up $21 per sqft per year.
Compared to the rest of the Greater Boston market, the Nashua submarket has smaller rates, so you should have no trouble finding a great deal in this depreciated submarket.
In the last 90 days, 143 listings have come on the market, so you'll want to check back regularly for new listings. About 34% of the listings in the Nashua are subleases, so you might be able to snag a great spot on a short term. 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 1,370 sqft. Most properties in this market are around 2 floors. Most buildings in this market were built in 1972 and are Class A.