Ebay
 

why do some people bid more money for items on Ebay than they cost (included P&P) down the shops!

...am I missing a trick?

No, it's all the mad people on ebay.

Indeed, some people assume that an item on e bay is cheaper than in the shops. Which in most cases is true. But some people go bidding mad and must win! Or don't do their homework about the cost in the shops.

Madness.