The hardest thing that I've ever had to do was figure out how much to charge for my services.
In the realm of management there really is no established set of guidelines of how much to actually charge for what it is you do.
In an ideal world I would just do it for free for the love of the art.
However, you try and pay your local power company with love and art and see if your lights will still be on when you get home. (Take it from me. I've done it. It does not work. (Oh to be young and ignorant again...I digress.)
There's always the fear of "Am I overcharging a client?"or "Am I undercharging a client?" " What if someone undercuts my bid?" Blah blah blah.
The simplest technique that I have found works the best is the price quote.
Add up the hours you estimate to be working on the project. Figure out how much money you need to actually live and SAVE (more on that in the future) times that by 25 percent for Uncle Sam (remember him?) Divide the money by the hours, times that by 100 and then quote that price.
Chances are if you think the number is too high or too low it probably is, but hey, that's why it's A QUOTE not the final invoice.
At the end of the day if you live in your greatness, and are a person of integrity, how much you charge will be the least of your concerns.