On average, listings lease in the $10's per square foot per year. The Dover submarket is going through a decline in rates. In the last 3 months, the median rate decreased $1 per sqft per year. That's a 4% decrease in rent.
Compared to the rest of the Greater Boston market, the Dover submarket has less expensive rates, so you should have no trouble finding a great deal in this depreciated region.
In the last 90 days, 14 listings have come on the market, which means listings are probably leasing quickly. 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 560 sqft. Most properties in this market are close to 2 floors. Most buildings in this region were built in 1900 and are Class Class B.