Heck; off-the-shelf tech can see you through your walls.
If you actually read the article you linked, you could find out that it's custom made hardware made from components which may be used in a wi-fi device, that's not the same as off-the-shelf.
"All the components we use are ones typically used in a Wi-Fi handheld device," she said.
Wi-Vi transmits two Wi-Fi signals, one of which is the inverse of the other.
Off-the-shelf stuff can't do this, but with components similar to that you can.