Most listings are in the $20's per square foot per year. The Portsmouth region is experiencing a a rise in rates. In the last 3 months, the median rate increased $22 per sqft per year.
Compared to the rest of the Greater Boston market, the Portsmouth submarket has less expensive rates, so you should have no trouble finding a great deal in this undervalued region.
In the last 90 days, 64 listings have come on the market, so you'll want to check back regularly for new listings. About 61% of the available space in the Portsmouth 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 available, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 2,200 sqft. Most buildings in this market are close to 2 stories. Most buildings in this market were built in 1930 and are Class A.