I charge for the readings I do, however the amount varies. depending on my overheads.
If I read from my home office or my local market (the latter is a $15 site for for a 4 hour aperture), I charge the least - $1 per minute.
If I read at a major Psychic Expo, where the site fee might be, say, $860 for a 3 x 3 metre space over a period of two 8 hour days, I charge about $1.65 per minute. In that case I have to make sure that I make enough to pay the site fee in the first day, so that the second day is profit. This kind of thing requires a fair bit of effort in setting up (I use dividers, hangings and other decor, as well as a volunteer to take bookings - always buying them a reward for their work - all of this has to be factored into the cost).
All of the above taking into account that I'm located in South Australia - my charges are in line with the going rate for my area.
I've been charging these rates for the past few years and can't look at raising them due to the flattened economy.
Fortunately I don't depend on this income, though I may do in future!