Most listings are in the $30's per square foot per year. The Leesburg region is going through a a boost in rates. In the last 3 months, the median rate rose $36 per sqft per year.
Compared to the rest of the Washington D.C. market, the Leesburg region has more expensive rates, and you'll have to negotiate above asking rent to be in this hot submarket.
In the last 90 days, 4 listings have been made available, which means listings are probably going fast. 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 2,290 sqft. Most properties in this area are approximately 3 stories. Most buildings in this market were built in 1990 and are Class B.