Steak 'n Shake is serving their individual steakburger for 75 cents until March 29th. You can add cheese for around 20 cents more. I think the deal is dine-in only, but it is a fun place to take the kids.
There is also a deal with the single steakburger, small fries and a drink. It was under $3.00. I would ask about if you are ordering more then the burger.