I am not a math person so I could be off. So I am sure someone will contradict me on this.
But, if a gallon of paint weights 4404.88 grams and there are 400 grams of paint (ink) in a cart. that makes 11.01 carts in a gallon
and at $150 a cart, they are making $1,651.50 a gallon. Nice mark up.