For those of us who value the bottom line and love quantitative analyses, let me offer a formula:

ROI of coaching= (Benefits of coaching-Cost to hire a coach)*100 / Cost to hire a coach

What are the benefits of coaching?

Self realization
Looking to the future with clarity
Living a more fulfilling life
Having an accountability buddy for your goals
Speed and power with which to achieve your goals
Bouncing ideas of possibilities
What other benefits can you think of?