English Experts

[EugenioTM]

Pay through the nose

Exemplos:

1.Many people end up paying through the nose for their car insurance policies.

2. Catherine is paying through the nose for fun and relaxation in her vacation.

3. That doesn't mean you have to pay through the nose for the privilege of an overdraft, however.

Fontes: Podcast inglesonline
Urban dictionary

Outras sugestões são bem-vindas!

[Simon Vasconcelos]

To splash out

They splashed out on their house.

[donay mendonça]

Opções:

Spend a lot of money
Spend big bucks

Big bucks:

A great deal of money, as in A swimming pool—that means you're spending big bucks. Buck has been slang for “dollar” since the mid-1800s. [Slang; second half of 1900s] - yourdictionary.com

[Telma Regina]

Eugênio
"Pay through the nose" means "be charged an exorbitant price" or that you give more money for something than it's worth.
"Gastar uma nota preta" is in another context. Means "to spend a lot of money".
When you spend a lot of money, it doesn't necessarily mean that you were overcharged. Do you agree?

[Thomas]

to pay an arm and a leg