Hey, Mandrake, I had (well, have) the same set of Dynamic Coins from the Paul Daniels range.
My recollection is that they were the most expensive item (excluding sets of effects). It cost something ridiculous, like £20, and this was in about 1981/82. Yes, you could get a couple of sets for that price now and still have change.
It is actually a very clever vanish, but like a few other good effects, this one seems to be very commonly produced and available in regular shops, so many people might be aware of it.
Mind you, I can remember fooling a cousin of mine (who must have been about 22/23 at the time) with a rather nice (but still plastic) version of the ball vase.
