$20 American is a little steep when I'll just steal one off a video store's wall in a few.....

Wait, I mean, "yup, good deal!"
In all seriousness, however, one might want to snatch these up. These are what the site calls "Advance One Sheets", meaning they may not be the final "official" movie poster, or one of several designs used to promote the film. And if the studio later picks a different design to be the lead promotional piece, these earlier posters become worth more $$$.
But obviously not always, and especially if this is the only poster that is released to promote the film or is the primary one.
Good find, Dave.