A few weeks ago I missed a sale for the EP-TA845XBEGGB 45W charger, annoyed at not getting the discount I decided to take a chance on ordering one from eBay. There are multiple listings for this charger at prices of £15-25.
The charger I received looks very convincing and could easily trick someone into thinking they've scored a bargain genuine item. However it is a counterfeit.
The easiest way to tell is the weight of the charger, according to the specifications on samsung.com, it should weigh 120.42g, the fake I received weighs 92 grams.
Other ways to tell:
If it looks too good to be true, it probably is. I expect many of the marketplace vendors on Amazon are also selling these fakes. Be careful out there, I'd recommend only buying direct from Samsung or a major retailer. Remember that a fake charger means fake safety certifications, don't risk your life or the lives of your loved ones. Saving a few pounds isn't worth a house fire.