On average, listings lease in the $10's per square foot per year. The Manassas Park region is experiencing a a boost in rates. In the last 3 months, the median rate increased $20 per sqft per year. That's a Inf% rise in rent.
Compared to the rest of the Washington D.C. market, the Manassas Park region has less expensive rates, so you should have no trouble finding a great deal in this undervalued submarket.
In the last 90 days, 4 listings have been made available, which means office spaces might be 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 1,000 sqft. Most buildings in this area were built in 1946.