Yeah I used to use these all the time. I worked a L'oreal promotion once and was sent home with literally 20 boxes of hair color! I have naturally golden/dark blonde hair and even trying to go a little blonder ended up bringing out teh red undertones in my hair. You definately need a pro to change your color!
If you're looking for a cheap way to repair your hair, I used to be a hair model for a couple different salons. They had trained stylists who were just being trained in a certain technique practice on our hair. I generally got amazing results and it was free (well I always tipped, but $10 for highlights is a great deal!)