Bucket shop

Bucket shop refers to a particular type of fraudulent business:

The term is used as a pejorative colloquialism to refer to different kinds of businesses, indicating that the speaker believes it is a fraud or scam. In this sense it might be used as a name for stock market, unregulated credit default swaps, or for heraldry scams.

The term is also used of airline ticket consolidators, though in this case there is no implication of fraud.