The monetary density of things

"It's a common figure of speech to say that x is worth its weight in y, where y is usually (but not always) gold. But most of us don't buy and weigh gold very often, so how do you connect that to real life? Does 'worth its weight' in pennies or $100 bills make any more sense? We have collected here a bunch of examples for different things that represent a wide range of monetary value per unit weight, in what might make a useful calibration chart for your future idiomatic usage." The monetary density of things