DIY Hair color help?

I usually go to the salon to get my hair dyed a few shades darker than my natural (very dark brown). Unfortunately it fades out pretty quickly, like within a few weeks. It is just too expensive to keep it up. I think I want to try to do it at home since I am just doing a one-process color..

Is there a brand in particular that is the best , just from the drugstore? Like Loreal, Feria, etc.......