it's money for old rope	łatwo zarobione pieniądze (money earned easily)
money does not grow on trees	pieniądze nie spadają z nieba (be careful with money as there is only a limited amount)
where's dirt, there's money	gdzie brud, tam pieniądze
a licence to print money	pieniądze za nic
fool and his money are soon parted	głupota i pieniądze nie idą w parze (stupid people spend money quickly)
money is no object	pieniądze nie mają znaczenia (you can spend as much as you like on something)