Many coaches undervalue their services. Like most coaches if you have decided to become a coach to help people fulfill their full potential or to make a difference to others' lives and making lots of money from it may be furthest from your mind. Because your focus is on your own personal satisfaction and fulfilling other values you may find yourself paying less attention to running your coaching practice as a business and charging an amount that will pay your bills.
Many coaches also value their services from the point of view of actual time spent directly with their client and fail to take into account the time and money spent in developing themselves as a coach. Consider the professional fees charged by lawyers and other professional services which reflect their specialist training.
You also need to factor in the costs of running your coaching practice. You cannot successfully run a coaching practice without a business mindset. The costs of your coaching should not only include the time spent with the client but also the costs of marketing your coaching practice, travel costs, administration costs etc. If you don't you will find yourself barely making a living or, worse still, making a loss which ultimately is not sustainable and you will be forced to find alternative work.
Another variation in fees arises from the wide ranging markets and their respective ability to pay. Coaches whose clients are senior executives in large corporate organizations charge far higher rates that many personal coaches who coach individual's funding the coaching themselves. And taking this to the other extreme there are other coaches who may have a passion for coaching those who are disadvantaged and the only means for funding this is through charity provision which may limit the fees a coach can charge. If you fall into the latter category, unless you have another source of income, consider coaching high paid clients whose fees will enable you to coach those who cannot pay so much.
Many coaches will also do coaching for free particularly when they are looking to gain experience. My view is that you charge something for your services even if it is a nominal amount. If you don't charge anything then this increases the chances of your client not valuing your services and is unlikely to do anything for your reputation as a professional coach who values their services.
So in summary when deciding what rates to charge remember the following:
Value the time and money invested into your own development as a professional coach
Take into account the whole costs of running your practice
Ensure you have better paying clients which will compensate for lower paying ones which give you satisfaction