I bought a new mains adaptor for my Nintendo DS Lite from an Ebay seller the other day. It charged the DS OK but when i attempted to remove the adaptor from the socket it fell to pieces exposing the wires inside!!!! Probably could have given me a nasty electric shock, but i carefuly removed it and swiftly put it in the bin.
Now I am adaptorless - but alive!!!
So please be careful when buying extremely cheap aftermarket adaptors for electricals. In future I will either buy an official adaptor or one made by a reputable company.