Most listings are in the $20's per square foot per year. The Fort Washington submarket is experiencing a an increase in rates. In the last 3 months, the median rate increased $21 per sqft per year.
Compared to the rest of the Washington D.C. market, the Fort Washington submarket has less expensive rates, so you should have no trouble finding a great deal in this depreciated region.
In the last 90 days, 2 listings have been posted online, which means spaces are probably leasing quickly. You'll want to be prepared to make an offer immediately. 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 1,120 sqft.