i mean i got this idea because i thought it was kinda cool and beautiful.
thats the thing, we see it as charghing someone as something maybe not appropriate.
But i sincerely believe its just an exchange, and its the opposite of not making trust. its actually building trust in a way, by trading with another human being and actually valuing it.
i mean even if its your friend alright, yeah he or she doesnt charge you through, but what if she or he would be appreciated for what they do by recieving something which has material value cuz at the end of the day material gets us through our lives. anyway, charging may not be so bad as it may seem to be, an exchange of values... just my 2c
A true friend would not ask for any material thing; I'm pretty sure a simple thank you and a warm hug would suffice and would be very much appreciated by those who listens.

Having a "fee" for such a simple act would only give someone a notion that you are only doing it for the money and that you're not really there to listen to their problems wholeheartedly.
and by the way this is listening services not true friend services but still you could consider me a friend:p