I'd say these have to be knockoffs. I've ordered a similiar set, from DX. The speakers were very tinny, and loud.
The infrared sensors didn't work when the nunchuck were plugged in. I didn't notice that until months after I purchased them that this was the case.
Also the official wii motion plus didn't work with my knockoffs. Mine look and feel very real, but they are not. I just suspect that these are the same.