がほしいのですが

would like …

→ が
phrase Rare #35,421
would like … A polite, indirect way to express wanting something, often used when making a request. The item wanted comes before が.
JA: 水がほしいのですが。
EN: I’d like some water, please.

何か飲み物がほしいのですが。

I'd like something to drink.

領収書がほしいのですが。

I’d like a receipt, please.

チーズがほしいのですが。

I’d like some cheese, please.

携帯電話がほしいのですが、支払うのに十分なお金がありません。

I want a mobile phone, but I don't have enough money to pay for it.

市内地図がほしいのですが。

I'd like a map of the city, please.