On average, listings lease in the $20's per square foot per year. The Manassas Park County region is seeing a decrease in rates. In the last 3 months, the median rate fell $6 per sqft per year. That's a 21% decline in rent.
In the last 90 days, 12 listings have been posted online, which means leases most likley are going fast. You'll want to be prepared to make an offer immediately. About 33% of the listings in the Manassas Park County are subleases, so you might be able to sign a shorter term by taking over a previous lease. 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 1,550 sqft. Most buildings in this market were built in 1983 and are Class A.