I don't want to pay for a color every four weeks, so I decided to start coloring my roots at home. A bit scary at first...but not as bad as it sounds. My greys are the "stubborn" ones that they mention in their fancy instructions so I've learned to leave the color in a few extra minutes..I also learned not to leave it in for 10 extra minutes. That made for black roots and light brown hair. Not pretty.
I've tried a few different permanent color in a box treatments and my favorite so far is Revlon Colorsilk Color 50. Each kit contains a bottle of ammonia-free colorant, cream color developer, after color conditioner, step-by-step instructions, and a pair of thin plastic gloves. The coloring process is easy; you simply mix the colorant and developer together, shake vigorously, and apply to the roots of your hair. You can buy one of those application brushes but I just use the gloves, squirt it on the greys and rub in. For roots you leave it in for 20 min, 25 for stubborn greys. Best part is it only costs $4.59 at CVS.
Doing my own hair color at home when my roots start to show allows me to have my appointments every 8 weeks rather than every 4 - 6 weeks which saves money and also helps me avoid the in between weeks of horrible grey roots.
Note: If you have hightlights, coloring your roots doesn't completely cover them. My highlights blend right away and start to show more and more after each wash.