Woot offers Just For Men Easy Comb-In Color, Hair Coloring for Men with Comb Applicator - Light Brown, A-25 for $7.21. Free shipping for Prime Members.

Product Description:
Just twist and comb. Eliminating grays is as easy as combing your hair. With Just For Men easy comb-in color, one tube of our patented no-mix formula meets one specially designed comb applicator. Give it 10 mins to blend away the grays, then wash it out, for a natural, gray-free look. Great for targeting gray areas or covering grays throughout your hair. Lasts up to 8 weeks until grays grow back. Can't decide between two shades? Try the lighter one first. You can always go darker later. 

• New look and name, same foolproof Autostop results, this patented formula automatically stops coloring after 10 minutes, so you can't go too dark. Just For Men Easy Comb-In Color, Light Brown, makes getting rid of your gray hair easy
• Using this no-mix men's hair coloring product is as easy as combing your hair. Simply attach the comb applicator to the pre-mixed color tube, comb into your hair to apply, wait ten minutes, and rinse your hair out in the shower
• Choose from 11 different shades ranging from sandy blond to rich black. When in doubt, always go with a lighter shade. Our gentle formula contains no ammonia or peroxide and is enhanced for better coverage from roots to ends