Smaller art is usually less expensive as well, so the non-gazillionaire is more likely to be able to afford it.
Kalman was born in Israel but moved to New York very young. You may recognize her from her kids books or her illustrations. She has books for grown ups but I remember one she did about a dog that eats stuff (What Pete Ate-From A-Z). She is in The New Yorker with frequency too. I think most of these paintings are gouache on paper.