[break] the bank

to financially ruin one due to having a very high cost

The idiom "break the bank" originates from the world of gambling, particularly from casino games like roulette or blackjack. In these games, the "bank" refers to the total amount of money or chips that the casino has available to pay out winnings to players. It is used to describe a situation where someone spends an exorbitant amount of money or exceeds their budget on a purchase, venture, or event.

She loves shopping for designer clothes, but she knows not to break the bank on expensive fashion items.
The company spared no expense on their latest advertising campaign, determined to make a big impact without breaking the bank.
The startup was cautious about spending and managed to launch their product successfully without breaking the bank.
They decided to take a vacation, but they didn't want to break the bank, so they chose a more affordable destination.
They wanted to throw an extravagant wedding, but they didn't want to break the bank, so they opted for a more budget-friendly celebration.