The mention of Gold and Silver being 'undervalued' is almost continuous in bullion circles... however I don't really understand the basis for making this claim of being undervalued.

How much would you be able to (trade) with a gram and/or Toz of pure gold 100 years ago?
How much would you be able to (trade) with a gram and/or Toz of pure silver 100 years ago?

I've been led to believe in the Roam empire, a common exchange for a Troy ounce of gold was a complete men attire including belt, shoes (sandles), toga, etc... Understanding our current pricing is extremely skewed by the various outsourced foreign production and slave labor environments, I'm pretty sure the same amount of gold today can result in a equal attire exchange assuming the products would be manufactured locally (tough to confirm).

So I ask, how can we illustrate the undervalued point to the masses?