I like to charge $20 for a 15 to 20 minute reading. I think it's probably too low, but I also don't like to schlepp around a lot of cash to make change. ATMs pay out in 20s. 20s are nice and easy. That's still $60 to $80 an hour.
I tend to use multiple small spreads when I read for someone, so I can do a lot in 15 to 20 minutes. Even the longest Russian Gypsy Fortune Telling Card layout - including searching for the images has only taken 7 minutes. That leaves time for the Tarot to provide the details to the questions the RGFCs brought up.
I can't hardly talk about any one card/image for more than a minute -- usually a lot less. Because the person is sitting there, you don't need to spend time describing the cards. I like to use the Golden Tarot and it likes to speak to the sitters in very literal terms frequently (soon to be ex husbands depicted by 10 of Swords, etc.), so I have time to answer multiple questions or drill in on the details in specific areas.
Umbrae's advice regarding calculating the time to do what you do -- the BEST advice on pricing I've ever gotten.
John Q comes in and really wants a reading, but only has a $5... or $0? Sure I'll read for you! Have a seat
Be prepared to give away a reading or two... consider it an offering to the 'Verse. You
will be rewarded for it, and rewarded well.
valeria