Re: Costs - worth every penny
I took my son (17), girlfriend and her son (13). We all enjoyed it but my son *loved* it. I can't remember him being so happy. I think the highlight for him was when a Jawa stole his watch.
He said that he's taught himself to lucid dream and has put himself in the scenario which Secret Cinema built.
I like the ban on phones/cameras, not for the secrecy but it meant the place wasn't full of people taking selfies.
I agree it's worth putting the effort into dressing up (something I did badly), I don't think it too expensive. My only criticism is that the toilets were outside and going to them broke the fourth wall.