Most listings are in the $30's per square foot per year. The Fairfax County region is seeing a a rise in rates. In the last 3 months, the median rate went up $5 per sqft per year. That's a 20% increase in rent.
In the last 90 days, 16 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 available, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,220 sqft. Most properties in this market are approximately 5 stories. Most buildings in this market were built in 1985 and are Class B.