If you are handy with soldering iron I can tell you how to build external battery/batteries so you would never need EN-EL15 or any other battery as long as your camera runs on 7V-7.4V. And external battery has at least 3x power of OEM.
Both of the Best Buys closest to me have stock on the shelf. If you check the website they show no stock but some of the stores do have stock. I bought one way before my D800 came in which I picked up Monday.