Peacefully yours...!!!

We see the $Yin-Yang$ sign as a philosophical symbol. So, Sara, on the occasion of a cultural event in her school, decided to paint the entire symbol on a really large canvas. Sara goes to the market to buy the required amount of paint (we can assume that she only does the black paint work, and leaves the white part as it is). Sara is confused about the minimum amount of money she should carry along with her. It is your task to help Sara calculate the minimum amount (in $dollars$ ). It costs $12$ $dollars$ to paint an area of $1$ $square meter$ on the canvas and the radius of the entire sign is $7$ $meters$ . Assume all curvatures to be equal.)