[CMOTD]

Does anybody know why these have become sought after all of a sudden?
   
There are loads of them about and until very recently they fetched a tenner or less on eBay. The price has suddenly doubled for no apparent reason, I sold one recently for £21 and another has just gone for £27. Ten different people were bidding on mine. These are used examples not mint boxed. It is nothing special, just a flashing light sequence so what is going on?