Warranties should be required and included from the get-go, or else chances are you want to avoid that supplier like the plague.
Lets talk about counterfeits now and why its easy to tell if someone is selling bootlegs.
See this for an example:
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This, is a Nintendo DS Counterfeit.
This would be illegal to sell on almost any place. It might even be illegal to sell it in your home town, except say off craiglist.
Nintendo does not endorse in any form this product.
I know this officially, because I have spoken to the seller at length.
He Shanghai2008 admits that there is no certificate with this item, and you can buy the warranty as optional.
This is 100% proof he is selling counterfeits or low quality knock-offs. Not only that, Shanghai2008 has a powerseller rating of 50%!!!!!!!! 50% of the buyers who purchased from him, have been unhappy and complained!!! That seals the deal. He's selling bootlegs, and admits it.
If THESE WERE legitimate 'replicas', the BOX would have the OFFICIAL Nintendo sign.
They would have a CERTIFICATE OF AUTHENTICITY, which is further proof Nintendo authorized them to go ahead and sell.
Since they do not, you want to run from them fast.
Shanghai2008 is the kind of seller/supplier you must always stay away from on DHGate or any wholesale store!!!
No matter what you do, you will get in trouble for selling his knock-offs. This is because none of them are certified. SHANGHAI 2008 IS SELLING BOOTLEG DS SYSTEMS !