Background Screens

Is there a place I can find images for backgrounds for my home movies?
Here's what I need. I'm working on a Star Wars type parody. The actors will be running around infront of a bluescreen and fighting infront of it. I need to get some sort of a background behind them. I was thinking about a Death Star (inside the death star) image, or maybe a futuristic setting that is indoors (like the end fight scene in Star Wars Episode 1, with Darth Maul). I've tried searching on google, but keep finding computer screen backgrounds and wallpapers, most being unusable.

If someone could tell me where I might find some backgrounds for movie scenes, I'd appreciate it.

Thanks