Casinos make it hard for those kind of places to survive. Pinocchio's is a great neighborhood kind of place. It's on Moana Lane near Kietzke and on Vista Boulevard in Sparks just north of Disc Drive. About $10 to $14 for an entree there. Don't know if that counts as cheap.
Maybe Jack's on Victorian near El Rancho in Sparks. It reopened after it it was closed because the owner wasn't paying taxes. The new owner pretty much kept the old menu. Breakfast for about $6 to $8.
Dunno what counts as cheap in your book.
There's two new, or relatively new, Vietnamese restaurants. I like both. I want to eat at each one before writing reviews on Chowhound. One is in El Cortez Hotel on West Second and Arlington. The other, Asian Noodles, is in the Costco shopping center on Plumb Lane and shares one wall with the original Sushi Pier and the other wall with what might be the west's worst Greek restaurant actually owned by a Greek. Asian Noodles is owned by the guy who used to own Kim Son in downtown Reno.
The Duck House on South Virginia Street in Reno across from the Peppermill can have some good inexpensive Chinese Food. As I always say, though, I'm suspicious of a restaurant called the Duck House so close to Virginia Lake.
The standard no brainer answer used to be the Nugget in downtown Reno for their $3.50 Awful Awful hamburger. That Nugget has changed hands and I understand they changed burgers. I haven't be in there to try it, but it was great greasy diner food.
Call the Coney Island Bar at East Fourth Street and Galletti Way in Sparks and see when they're offering garlic soup next and get their garlic soup and sandwich for about $7. The sandwich is good but I think the garlic soup counts as a Chowhound must.
Several Mexican restaurants with good burritos and tacos cheap. Try the tacos at Fresh Mex on keystone or a Burrito at Tacquieria La Mihochicana (I can't spell it) near Big 5 sporting goods on South Virgnia and Kietzke Lane.