 I go every week, Yellen replied. It's sticker shock, isn't it? Just when you look at shipping costs, those have come down. Global food commodity prices have also come down, but food prices still remain high. Should the U.S. invest in agriculture to boost the food supply in this country? Sean Berger asked. Yellen, who's worth an estimated $20 million, began to reply no before Sean Berger even finished her question.