Go to Singapore Bistro on 19th in between M and L. They have a good HH special going on there - selected apps fro 1.95 and nigiri sushi under $1.
If you're ever in Rockville go to Maria's Bakery (I talk about them alot, I know. I swear I don't work there or own the joint!) - it's definitely cheap, filling eats. Yesterday I got 3 drinks - HK milk tea, iced lemon tea - tastes like a B'more 1/2 and 1/2, milk bubble tea, wonton lo mein (enough for 2 people) and a pineapple bun for 14 bucks w/ tax.
I'd also go to the prepared section of ethnic markets - Han Ah Reum, Lotte, Maxim, Kam San - and get some food there.
Funny, it's always the ethnic eats that are reasonable on the wallet! (Well, almost always...)