3rd Party EN-EL15 ?

Expecting my D800 delivery today (woohoo - as long as Citylink don't mess up) - I'm investigating things like spare batteries etc.

I don't seem to be able to fid any good, 3rd party versions of the EN-EL15

Are there any (UK) ?

The only version I've seen was 1400mAh - significantly short of the Nikon Original 1900mAh.

Are the electronics in them too hard to copy or something ? Will I have to bite the bullet and get a Nikon Original ?

I was expecting that someone like Hahanel would surely have brought one out by now since the D7000 has been out for a while.

Don't like paying £50-70 for something like that.