Not in the heart of down town but:

Akida in the fan is a fun spot and has very good price Katsu and other entrees. Sushi is a bit more expensive, but reasonable unless you go for the over the top special rolls.

Edos Squid has big portions of pasta for under $20. Meats and seafood are more. I think it’s a cool space, but very loud and crowded.

Beauvine, for burgers.

Takara Ramen was reasonable $28 for 2 people 3 dishes.

Liberty Public House

Average is probably ~$15, good portion sizes at reasonable prices and the food is good.

If it does not have to be downtown, on Monday's the two local Sedona Taphouse restaurants have a Dine out for charity menu where the dishes are 1/2 off. its an 8oz Flatiron steak, 8oz chicken breast, or their Salmon entre for between $10-$13 https://sedonataphouse.com/locations/midlothian-va/

I work and live downtown and there are plenty of options for <$20 a plate dinner: Capital Ale House, Chicano's Cocina, Casa Fiesta, Mom's Siam, Sine (I think their food is highly underrated due to their rep as a bros-getting-hammered bar), Wong Gonzales (highly recommend the bowls/pots which come in at right under $20).

http://caferustika.com/menus nothing over $20 and you’ll probably have leftovers for lunch the next day.

2nd for LPH but they are not open today, just wed-sun

Chicanos is solid

Rosie's

I love Wong Gonzalez

Taphouse has a really good lunch too, but they're closed Monday/Tuesday

Oh yeah I always forget that one! Great lunch indeed.

Also not in downtown.