I would wait until a company like Anker or someone like Mugen makes this available:
[HLI-N7100XL] Buy Mugen Power 6400mAh Extended Battery for Samsung Galaxy Note 2 with Battery Door
A little more pricey for sure...I would not trust an $8 extended battery. I had some Andida batteries for my Note I that were pretty good but I have not seen them.
Also, you might want to make sure that upgrading to batteries like these does not affect NFC functionality if thats important.