In reply to keith-ratcliffe:
If the projection is just relying on the light from a phone screen, I can't imagine it would be able to project very far unless you are in a completely pitch black room.
I had a small projector that plugged directly into an iphone, I guess similar to the ones you have found for £65 which was good for projecting an image about the same size as a 32" tv about 1.5m from the projector. Any further away and the image was not bright enough. I doubt a £65 projector will have any kind of sound output either, so you'll need a decent pair of speakers to plug in.
They might be ok for sharing the odd photo, but by the time you've gone and dug the thing out of a drawer, closed the curtains, found a blank surface to project onto, focussed it. You may as well just pass the phone round!
Post edited at 15:43