If you can't find one at a carrier store, bestbuy, or a local retail outlet, then all you're left with is Amazon or ebay. There are a lot of fakes sold at Amazon and ebay, so if it were me and I was going to look for one there, I would search for an OEM "Retail package"... no bulk stuff. Even then, it might be a fake, so read the seller's feedback, consider where the seller is located, (USA, China, etc), and if it looks legit, then you'll just have to take your chances. Some retail stores have ebay stores also, so you can also look up contact info which might be posted and give them a call.