I have seen a few threads recently about people with very noisy linear modules. And plenty of people have destroyed their print heads with plastic blobs. People complain about noisy power supplies occasionally. If you don’t want to keep them as your own personal spares, and don’t mind waiting a bit, I’m sure somebody from the forums will take them off your hands.
I mostly see people selling whole units, not parts. I really don’t have any advice on where to start with pricing. Search the forums for “for sale” (make sure you’re searching “in all topics and posts” not “in this post”) , and see if you can get a feel for how those sales went.