I used to color and highlight my own hair when I was younger. I bought all my dye, developer, foil,and brushes from the local beauty supply store. The only reason I stopped doing my own hair was because my vision has gotten worse as I have aged, so it is hard for me to judge color processing time with no glasses on.
I now pay to have a professional do my hair. To be honest, its worth every penny. I sit back and relax in a chair, she does my hair. No more worrying about messes in my house, color jobs over processing or not taking on my hair, etc.
I'll also give everyone one piece of advice...hairdressers secretly love it when you color your own hair, because they can charge three times as much to color correct it than the initial salon dye job would have cost. So if you color your hair at home, just keep in mind it becomes more expensive to fix if you mess it up or damage your hair.