The average rate of tattoo artists is about $150 to $200 per hour. A full back tattoo takes 20-40 hours depending on the design, style and how much of the back is used.
If you want to get a full-length back tattoo, in high definition, and well saturated colors of Japanese mythical creatures such as a dragon, cherry blossom clouds, then prepare for about $5,000-$8,000 before tips.