Where to find creepy old wallpaper?

In years past, my haunt has consisted of basic black walls with a few rooms having 'Scene Setters' up to make it look like a kitchen, dining room, etc. which added some needed variety but still wasn’t super impressive. One of the things that always gets me about Pro Haunts is how realistic their rooms are. You really could believe you are in a freaking deranged mansion about to be murdered because the walls are cracked and crumbling and the walls all look like you are walking through a Victorian home.

So the question is - aside from painting, how do you make your walls and scenes look more realistic? Does anyone know where someone can buy vintage looking wallpaper for bedroom scenes, etc. similar to the picture below? I'm fine with distressing it myself I just don’t even know where to start here. Any pointers or links would be much appreciated!! Thanks!