money down the drain
Money that is wasted, squandered, or spent unnecessarily. My degree in literature has so far been a lot of money down the drain, as the only jobs I've been able to get have been in restaurants waiting tables. All of these gadgets you buy are just money down the drain, if you ask me.
ˌmoney down the ˈdrain
(informal) a waste of money: Her father feels that all her expensive education will just be money down the drain if she gets a job in a cafe.