I saw this on Facebook too. I emailed the photos to Bowers and Wilkins Australia as I had my suspicions. This is there reply:
"Thanks for getting in touch. Bowers & Wilkins car audio loudspeakers are not available for separate purchase through the Bowers & Wilkins dealer network and may only be ordered as an option on selected vehicles from BMW and other manufacturers.
It is highly unusual that a store is selling them as an after-market option, suggesting that they could only have been come from an existing vehicle.
The branding ‘B&W’ immediately raises suspicions, as this is not in line with company brand usage guidelines. The cone material is also not one that is recognisably Bowers & Wilkins.
We suggest proceeding with caution and asking the seller to provide more evidence of their authenticity."