You'd have to excercise your judgement as to the reliability of the seller. If the price is too good to be true, it's likely to be a counterfeit knockoff. Also, if the seller cheats you and you paid by a credit card, there is buyer protection. You can check the ratings the seller has received. A seller who regularly cheats his customers is unlikely to have good ratings.
Sellers advertising a product on Amazon, then delivering a cheap Chineses counterfeit, has become a big issue lately. So much so that "60 Minutes" did a special on it awhile ago. This happened to me on two occasions. In my case, the the seller refunded my payment. Amazon tries to stay out of it, even though they are aware of it.
I noticed that the "I-NEED" case seller has no feedback of any type. Not even a history. The case looks to be a cheap knock-off of an OtterBox Defender case.