The typical asking rate per listing is in the $30's per square foot per year. The Greenbelt region is experiencing a a rise in rates. In the last 3 months, the median rate rose $30 per sqft per year.
Compared to the rest of the Washington D.C. market, the Greenbelt submarket has smaller rates, so you should have no trouble finding a great deal in this undervalued submarket.
In the last 90 days, 10 listings have been made available, which means new listings might be going fast. You'll want to be prepared to make an offer immediately. About 110% of the available leases in the Greenbelt 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 posted, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,280 sqft. Most buildings in this area are approximately 8 floors. Most buildings in this area were built in 1986 and are Class A.