To break the bank is to cost more than you can possibly afford. It will not break the bank.
It is used in the negative far more often, to say something is affordable after all. The bank is the gambling house, which a big enough win was said to break.
1phrasebreak the bankTo cost more than you can possibly afford.
“A night out once a month will not break the bank.”
break the bank is a phrase.
Practised in Idioms