On average, listings lease in the $0's per square foot per year. The Dover submarket is going through a decline in rates. In the last 3 months, the median rate fell $18 per sqft per year. That's a 100% decline in rent.
In the last 90 days, 4 listings have been made available, which means spaces 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 on the market, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around sqft. Most properties in this area are around 2 floors. Most buildings in this area were built in 1968 and are Class C.