Depends on what you mean by ‘expensive’ ;) … is it absolute dollars, or relative dollars (e.g. fraction of income), or is it time spent earning each dollar, or

Depends on what you mean by ‘expensive’ ;) … is it absolute dollars, or relative dollars (e.g. fraction of income), or is it time spent earning each dollar, or the effects on health, happiness, and longevity from not having enough dollars? Looking at that list, there might only be one (misleading?) metric that makes being rich more expensive than being poor. But how rich and how poor are we talking?