Help - WTB Camera Grip for Nikon D3100 - Best one or Next to Best one & Best Price

I have looked on Ebay. I've looked on Amazon. Now I am throughly confused by all the diffrent ones that I have looked at on Ebay & Amazon. Seems like they range in price anywhere from $ 20.00 to   $ 70.00 in price. I'm not sure if Nikon actually manufactures one or not but I know from my recent Nikon purchase that it wont be priced anywhere close to the ones I've looked at so.... ? I dont really want to wait for it to ship from Hong Kong or anywhere else in China. I need some feedback from folks who have one and their likes and or dislikes on what they have and where did they get it from.