Trade Me says it is not illegal to sell police lights online.
It comes as police in Whangarei search for a group of people who have been posing as police officers, with red and blue flashing lights on top of their red Holden Commodore.
Head of Trust and Safety Jon Duffy says students often buy them for their flat, or people buy them for discos.
But he says individuals are responsible for how they use the products.
"If people were to purchase these lights and install them in their vehicles, and then use them in a way that caused the impression that they were police officers, then that would be an offence.
"Yeah, we'd be quite concerned to hear about that."