Extending my hair color

I try to get my hair done about every 8 - 10 weeks and sometimes I even go up to 12 weeks.  I have the great pleasure of being very gray headed.  If I were to completely let it go I would be about 80% gray.  PS I am not even 35 yet!!  This means I have to stay on top of my hair color and also be budget friendly.  I start to need a touch up at about 4 weeks.  If I am going really long between I will use the root touch up and if it's going to be more towards the 10 -12 weeks than I use the root touch up at 4 weeks  followed by the whole head kit at around 8-9 weeks.

Root Touch Up: L'Oreal Root Rescue:  Dark Brown (7.00)

http://www.ulta.com/ulta/browse/productDetail.jsp?skuId=2219022&productId=xlsImpprod2360101&navAction=push&navCount=1&categoryId=cat120040



Whole Head: L'Oreal Healthy Look Creme Gloss (9.00): Medium Brown Truffle
I like this one because it only takes 10 minutes.

http://www.ulta.com/ulta/browse/productDetail.jsp?skuId=2215731&productId=xlsImpprod2300077&navAction=push&navCount=1&categoryId=cat120040



Good Housekeeping gave this hair color great reviews for brunettes.  I am going to give it a try next time and see how it does.  Here is the link to this article.  It breaks it down by best color for hair shades.  Just in case your not a brunette.
http://www.goodhousekeeping.com/product-reviews/beauty-products/hair-dye-reviews/best-home-hair-color#slide-1

Revlon Colorsilk (4.00): Dark Brown



Do you dye your hair at home to extend your time between appointments? What do you use?