Up for auction on eBay is a rare Vectrex 3D Imager accompanied by three cartridges and everything else (not much to be honest) you see on the pic posted above. And, yes, if you've never seen one of those headsets, they do exactly what you imagine them to: bring proper 3D to Vectrex gaming. And as the 3D Imager was released back in early 1984 it is indeed the very first virtual reality kit to ever hit homes worldwide.
The Vectrex 3D Imager on auction is in good condition and apparently works fine, as do the games that come along. The seller's shipping to quite a few places worldwide.