Unless the seller knows his stuff, he has no way of knowing whether it was late or early 1800s.
If it is dirty and pitted, then 50$ is probably not a great deal. Not a bad deal either if it turns out to be a good shaver. And I could always be wrong. I am married so it's not abnormal

Let's put it like this: I am Belgian, and I would not pick it up for that price unless it looked great.