Linguica, preferably Gaspar's?
Two places come to mind. One is the A & H Seafood Market in Bethesda. I believe the owners are Portuguese, perhaps Spanish. Good selection, worth the drive http://www.aandhseafood.com/.
The other is the Euro Latin Market in Arlington, VA. Euro-Latino Grocery, 2700 Pershing Dr. (at Washington Blvd.), Arlington. 703-524-6800. Farther for you, but great selection as well.