On average, listings lease in the $30's per square foot per year. The Fairfax region is experiencing a decrease in rates. In the last 3 months, the median rate fell $1 per sqft per year. That's a 2% decrease in rent.
Compared to the rest of the Washington D.C. market, the Fairfax submarket has lower rates, so you should have no trouble finding a great deal in this undervalued submarket.
In the last 90 days, 31 listings have been made available, which means new availabilities might be 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 1,930 sqft. Most buildings in this area are around 5 stories. Most buildings in this area were built in 1985 and are Class B.