DVD
I found this movie in a large department store under the Direct Souce label.
It is
a double movie dvd and is paired with Charade.This is in Canada
The same double-feature DVD is currently available on Amazon.com. One of My Wives is also currently available (for watching or download) on Amazon Prime. And Amazon has a VHS tape as well.
I've got all except the VHS, and found the picture quality quite watchable, but not much better than YouTube, where this movie is currently available for free. I don't know if it's possible to download it from YouTube, though, so if you want a physical copy, Amazon is a good source.