@Alex – Unfortunately ebay isn’t actually a cosmic ball – it’s two other unrelated products. Amazon say they are currently unavailable (as they’ve been for the last year).
@Susanne – I’d made this something of a pet project, because I thought they were so wonderful. It looks like the Chinese manufacturer no longer makes them (there is not really a mass market), so you only intermittently find places in the UK which are selling old stock.
Instead, I recommend a glowing Elvis bath duck from places like JustDucks. Advantages: a mass market so they’ll be around for a long time, a little more robust. Disadvantages: not quite as bright so it helps to darken the room, doesn’t make a sound so not quite as much impact. However, I’ve tried these out with different audiences and they get a very similar reception. We also showed that they work with a ring of 60 people, during an event at one of my schools. Surprisingly “street” year 9 boys were persuaded to hold hands with each other to join in.
A note on bath ducks that make a sound – I haven’t been able to find any (despite extensive research…) which make a sound that switches off instantly when you let go of the contacts (like the cosmic ball). All of them trigger a set sequence, which I feel is so confusing that it’s not worth having.