There are a lot of things that go into it like electricity cost, hardware cost and type of hardware too. If you order hardware from a supplier like Butterfly labs which has major shipping delays that's also a consideration since by the time your order arrives the difficulty and value of the coin may be vastly different.
Ok but surely someone can give a range. The average mining operation is spending how much per coin?
Whatever the number is, is theoretically the lowest the price of a coin should go. Or at least the risk of it going lower gets low enough to not worry me so much.