No, it's not really idiomatic - at least in American English. It implies many things that are expressed in other idioms, sayings and stereotypes ("he pinches pennies so hard they squeak" or "my family is shopping and so I'm crying" or a joke like "The doctor wrote me a prescription for pain medicine. I said, 'Dr, I'm not in pain,' and he said 'No, but you will be when you get my bill!' ")
Okay, this is a bit "tricky", because money is actually implied. When someone says "ξοδεύω" in Greek, they're usually talking about themselves either time or money.
When they are referring to time, χρόνος (or some form of it, like χρόνια, βδομάδες, μέρες etc) is actually mentioned.
When they are referring to money, χρήματα could be ommited, because it's somehow implied, in some cases, like this one. It's kind of an idiom. I think I've heard an English version of it (not quite the same as this one) , something like "Paying with cash hurts." It has kind of the same meaning.
But, since it's idiomatic, It hurts when I spend is accepted as a translation ^.^
It hurts me when I spent.
Spent is the past tense though... Also, it hurts me = με πονάει. It's better to stick with a translation that retains as many features of the original as possible if it's also correct in the target language. It may not be the most natural but it does give you a good idea of what the language you're learning works like, what its structures are. :)