Most listings are in the $30's per square foot per year. The Fairfax County region is seeing 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.
In the last 90 days, 25 listings have come on the market, which means spaces most likley are 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 2,340 sqft. Most properties in this region are approximately 5 stories. Most buildings in this market were built in 1985 and are Class B.