The typical asking rate per listing is in the $20's per square foot per year. The Bull Run submarket is going through a an increase in rates. In the last 3 months, the median rate rose $1 per sqft per year. That's a 2% increase in rent.
Compared to the rest of the Washington D.C. market, the Bull Run submarket has smaller rates, so you should have no trouble finding a great deal in this depreciated region.
In the last 90 days, 40 listings have been made available, which means new availabilities 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 1,960 sqft. Most properties in this market are approximately 2 floors. Most buildings in this region were built in 1988 and are Class B.