I have always used compatibles in my cameras. I've used Phottix branded EN-EL3e and EN-EL4 batteries from eBay and never had any problem. You can buy more of them for the lower price than originals, rotate them and they will last longer due to less power cycles.
I find it ridiculous than Nikon completely changed latest gens of cameras so everybody who is using both old and new gen bodies has to have two sets of batteries, chargers and adapters.
I know there was that stupid Japanese regulation about max capacity vs volume, but if they were clever they could design a better solution - like just different battery doors and allow us to use both old and new batteries in the new bodies or at least keep chargers and power adapters.