I am with KimmerB. I hate spending the money on coloring too. But I decided to 'experiment'. The colors that you have to mix; on the ones I have are each 2 ounces each. Save an extra bottle OR I have used a small corell bowl and put it on the scales before I turn it on; measure out - very carefully - 1/2 ounce of each product into the bowl; then mix it well. Because my hair is very short and for now most of the gray is around my face, the mixture is more than enough to do the job instead of having the hair sopping wet with color. A box will last me 4 treatments. Less than a buck for each coloring. Just an idea.
I don't have lots of gray but enough that it makes me feel older than I am - or maybe just older than I want to admit I really am. So far this above works for me - for now.