If you've driven down South Congress, chances are you've seen the little airstream trailer with a pink rotating cupcake on top and a line out to the street. That's Hey Cupcake! They offer all kinds of cake flavors, from vanilla and chocolate to red velvet and carrot cake, and the icing comes in vanilla, chocolate, butter cream, strawberry or regular cream cheese. They are huge cupcakes, so you get a lot for under $3.
Hours vary by location.