Hello and welcome!
If I'm not mistaken, I think the NFC chip is incorporated into the battery, so be sure to make sure the one you pick out has it. (if I'm wrong, then someone correct me).
Also, I would venture to say that in my opinion, stay away from Ebay and look at Amazon for Samsung brand, or even the Anker brand. I've used the Anker brand in my Evo and it performed really well.