expense

the use of money, time, or effort:

Buying a bigger car has proved to be well worth the expense.

We've just had a new garage built at great expense.

We went on holiday at my father's expense (= he paid for it).

It's silly to go to the expense of (= spend money on) buying new clothes when you don't really need them.

something that makes you spend money:

Our biggest expense this year was our summer holiday.

We need to cut down on our expenses.