Most listings are in the $20's per square foot per year. The Portsmouth submarket is going through a decline in rates. In the last 3 months, the median rate fell $1 per sqft per year. That's a 3% decrease in rent.
Compared to the rest of the Greater Boston market, the Portsmouth submarket has lower rates, so you should have no trouble finding a great deal in this depreciated region.
In the last 90 days, 64 listings have been made available, so you'll want to check back regularly for new listings. About 31% of the listings in the Portsmouth 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 available, so finding a space for a small business might be tough.
Even though the median size is 2,660 sqft, there are still 0 new listings below 2,000 sqft. Most properties in this market are around 2 floors. Most buildings in this region were built in 1930 and are Class A.