donuts for The Yearbook Mystery Box ?

You have to figure out how many KEMs you can buy per round and still increase your cash. Simple method: write down your cash at the beginning of the day, then again at the end. Subtract one from the other and if it's a positive number you're ok.

I have a boxed in area defined by stuff that can't be sold, so when I sell the KEMs I don't sell other stuff by accident. As you can see I've already picked up a few donuts - despite a goof up earlier today when I forgot to tap them in, sell them and replace for the next round (I was hungry and not thinking).