The typical asking rate per listing is in the $20's per square foot per year. The Manassas submarket is seeing a an increase in rates. In the last 3 months, the median rate increased $12 per sqft per year. That's a 70% increase in rent.
Compared to the rest of the Washington D.C. market, the Manassas submarket has less expensive rates, so you should have no trouble finding a great deal in this undervalued submarket.
In the last 90 days, 26 listings have been made available, which means office spaces are probably 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 1,410 sqft. Most buildings in this area are close to 2 floors. Most buildings in this region were built in 1989 and are Class B.