Black Lion in columbia heights might fit the bill. Avoid buying standard products (all overpriced) but they have a good selection of spices sold in bulk containers. They also sell a lot of traditional ethiopian food and cookware. In the back, there is a butcher counter but it's only operating occasionally and I believe they cater to the ethiopian community as well (not sure exactly what they stock).

They sell solid sambusas by the cash register too. I always find something interesting when I pop by.