Most listings are in the $20's per square foot per year. The Lansdowne region is going through a a rise in rates. In the last 3 months, the median rate went up $26 per sqft per year.
Compared to the rest of the Washington D.C. market, the Lansdowne submarket has less expensive rates, so you should have no trouble finding a great deal in this depreciated submarket.
In the last 90 days, 1 listings have been posted online, which means spaces are probably going fast. You'll want to be prepared to make an offer immediately. About 100% of the available leases in the Lansdowne 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 1,990 sqft. Most buildings in this area were built in 2007 and are Class A.