Compared to the rest of the Washington D.C. market, the Lorton submarket has less expensive rates, so you should have no trouble finding a great deal in this undervalued region.
In the last 90 days, 5 listings have been made available, which means new availabilities 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 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 600 sqft. Most buildings in this region are around 2 floors. Most buildings in this region were built in 1985 and are Class A.