"Shirt of elastic fabric (clings to body) at a length that covers the shorts’ waist band, of black or white color, and displaying at least 10% of the color of the rank (belt) to which the athlete belongs. Shirts that are 100% the color of the rank (belt) the athlete belongs to are also acceptable."
You do not need to buy an expensive rash guard from the internet etc..
This is NOT acceptable as the body as to be white or black and NOT other color like blue
Just buy a rash guard that is of the color of your belt.
So if you are a white belt, just buy a cheap white rash guard.
Blue belt, buy a blue rash guard etc..
Or you could buy the black rash guard that NZ grappler is selling for NZD 60 on the day on the comp.