Many electric razors (at last in Germany) consists of a head (which is a bit plastic and the blades) and separate handle (which has the electric parts). So reusing the handles is just fine as they don't get into contact with any cut (through desinfect them anyway).

For classical razors you could have a culture of getting a high quality one when you start needing it and then keep it for a lifetime if possible (through you have to sharpen it from time to time).