I bought this kit at Imperial Shopping Worlds, at a third floor school supplies shop (link to where is here).
It is a demonstration of a dynamo powered by the water wheel that lights a little light (LED I think).
I have to say it's not so good. The dynamo doesn't push into the wheel as it says in the instructions, I've had to glue it instead, as you an see from the photo, Despite that I did get it to work pretty well.
Cost 190 Baht, about $6, 4.5 Euros.