Best way to do ghosts in haunted house?

We have a room in a community haunted barn and we are going with a Coraline theme. This is a very low-tech thing without a lot of funds, so I can't go too extravagant. I would like to have the ghost children from the movie projected onto a wall but I can't figure out the best way to do it. It'll be on the far end of a long hallway.

Of course my first choice would be to use a projector....but we don't have one so I'd have to buy one myself if I want to use one. If I go this route, I was thinking about a DBPower T20 LCD mini projector, since it's fairly cheap and reviews are pretty good. But since it's at the end of a long hallway, I'm not sure where I'd put the projector that the people wouldn't be walking in front of it. I assume I couldn't get too close to the wall and have it be very big? Possibly mount it up high? The walls are all black plastic - would I need a white screen? I don't mind if it's not SUPER clear since it's kind of just a diversion thing so they're looking at that instead of what's coming around the corner.

I did try to make a shoebox projector with a smart phone and a magnifying glass but I didn't think it worked worth a darn.

Any suggestions?