Tony,
I use Garneir Nutreese, #60, Acorn, which looks very natural, takes just 8 minutes to apply just prior to taking a shower, lasts for about 20 washings. Prices vary from $6 to $8, and you can always find cupons in the mailers that offer up to $3 off the price.
I do NOT recommend using some of the men's hair coloring agents - they look like shoe polish, or worse yet, a sharpie.

I just wish I had more hair to dye.
Gary

_________________________
PSR-S950, TC Helicon Harmony-M, Digitech VR, Samson Q7, Sennheiser E855, Custom Console, and lots of other silly stuff!
K+E=W (Knowledge Plus Experience = Wisdom.)