Bitcoins cost of production are about $1
1.5$ - 2$
You forget the extras needed for production, on small scale or large scale bitcoin mining.
Even at $2 cost of production the price of bitcoins has overshot any sense of reality.
Even with a couple of months worth of increased difficulty built into the current price it's current price is a bubble.
What are the barriers to entry a $700 -$1000 machine.
It takes very little knowledge to start mining for bitcoins.
This will end very badly for anyone who has invested in bitcoins in the last 30 days