If grey hair is the bane of your existence (and of your wallet), perhaps you'd be up for a solution more evolved than dye.
In an American Chemical Society Journal article called "Current Trends in the Chemistry of Permanent Hair Dyeing," authors Robert Christie and Olivier Morel say that scientists are already working on ways to reboot the natural pigment production in hair via gene therapy. The idea is to find a way to reverse, even prevent grey hair.
In fact, turns out that in 2000, scientists found a way to trigger temporary hair-follicle re-pigmentation in rats. The trick is, according to this ABC news story, "Could Genetics Keep Your Hair from Going Gray", targeting pigment-producing cells in the hair without affecting pigmentation elsewhere on the body. Erk.
How do you feel about one day tackling your greys with gene therapy? Or maybe permanent hair colour in a no-drip mousse formula is enough for you right now?