Mostly for people who sell tattoos a lot.
If you have excel make a chart that tells you how much a tattoo is depending on the price of ink. Most of the chart uses formulas, so that is important to know how to do. The only thing that will need to change in the chart once it is completed is the price for ink, they change day to day.
It takes long to make & can get messy when trying to figure out formulas, but it is useful. I made a complete chart and it is easy tell which tattoos are a profit & which are not after checking what their price is at the market place.