I charge for tarot readings. I base my rates on what is customary in my local market, on what I feel is a fair value for what I offer. There are two main reasons I do this:
1. It helps value what I do, which makes me a better reader. To offer readings for free isn't exactly pearls before swine, but it does set up a situation that is out of balance. Too much giving without any giving in return dries out the well, and a dry tarot reader is a lousy tarot reader. The current vocab for this kind of give-and-take is "energy exchange." Sounds reasonable to me.
2. It helps my clients value what they get. It's a truism across the board -- people value things more when they have an investment in them. Services such as tarot are no different. I always say that during a reading, my client is the one doing the hard work, and that's true -- I'm the interpreter, the guide, the helper (which is hard enough, this is true, but no matter how well I do MY job, if the client isn't doing HER job, then all my efforts are in vain).