The typical asking rate per listing is in the $20's per square foot per year. The Loudoun County region is seeing a decline in rates. In the last 3 months, the median rate fell $3 per sqft per year. That's a 9% decrease in rent.
In the last 90 days, 109 listings have come on the market, so you'll want to check back regularly for new listings. About 1% of the listings in the Loudoun County are subleases, so you will probably need to sign a longer term lease with the landlord directly. There aren't many listings below 2,000 square feet available, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 2,500 sqft. Most buildings in this region are close to 1 stories. Most buildings in this market were built in 2000 and are Class A.