Can I touch up my roots with drugstore hair dye considering my hair is colored using salon dye?

I think it all comes down to how much you will be upset if it screws up. I myself have always used the box, even mixed two colors together but I am not a real stickler about my hair. Have you seen the colors people have out there? I would never pay for a salon color.Too expensive. I would try it but only if you won't resort to like shaving your head if it doesn't turn out. Good luck! ps I have never been disappointed enough to do that!