brass screws

Broke down my first microwave today. Almost all of the screws holding the thing together were brass. How common or rare is this? Just something I have to keep my eyes open for I guess, even if the extra value isn't much I will take it!

When I have the time, I throw all scrrews and little stuff together and go through it with a magnet. All steel goes in one bucket, and the rest all gets swept into another container for future visual seperation (brass, aluminum, stainless). I have never gotten around to that seperation yet, but one day it may happen.

Not sure of the commonality of those being brass though.