Sinking feeling

Referência: http://igetitcomics.com/2012/02/12/sinking-feeling/

Cost (somebody) an arm and a leg

Referência: http://igetitcomics.com/2012/02/26/cost-somebody-an-arm-and-a-leg/

High and dry

If you are left high and dry, you find yourself in a difficult situation without help or resources.

Example: When her husband walked out on her, Amanda was left high and dry with two kids to raise.

Down in the mouth

This expression is used when someone looks unhappy, discouraged
or depressed.

Example: "You look a bit down in the mouth. What's the matter?"