In order to express having enough financial means to make a certain purchase (or, for such a purchase to make financial sense) Germans use the construction “sich etwas leisten”:

– “Ich kann mir das Auto nicht leisten.” – “I can’t afford that car.”
– “Er kann es sich bestimmt leisten.” – “Surely he can afford it.”

Just like in English, you can also use “sich etwas leisten” for situations that have nothing to do with money:

– “We can’t afford not to do it.” – “Wir können es uns nicht leisten es nicht zu tun.”

The word “affordable”, on the other hand, is best translated as “erschwinglich” (or “bezahlbar”):

– “Massenproduktion hat die Technik nun erschwinglich gemacht.” – “Mass production has made the technology affordable now.”