content: I think of it this way: We have spent centuries, even millennia perfecting and making more efficient the growing of plants outdoors.  This whole indoor vertical stuff is a relatively recent advancement, and a major change to the 'normal' way of doing things.  The fact that the cost is already only twice that of the tried and true, perfected-over-millennia method is pretty astounding.  Much like renewables vs non for energy, it won't take that long in the scheme of things for this to reach parity and eventually surpass older methods.