Does the cost of gold reflect the amount of money it takes to produce one troy ounce?
Or could it be that it's scarce and has properties that have increased it's value over the centuries?
I have a great business plan for you: Go mine gold at $400 per Kg and sell it at $13,000. Why buy a gold watch or a gold bar when you can go straight to the source.
As far as I know the price for mining a single troy ounce currently is >500 USD. If it would be possible for everybody to dig a hole in their garden to mine an ounce with half an hour work it would be worth near nothing. It is pretty sure that you as an individual cannot effectively mine gold for less money then it is sold.
Could you please provide a reference for the 400 USD per Kg statement?