It might be worth giving the Apple Store or online support another shot.
I was in basically the exact same position a month ago (pros bought launch week, very out of warranty, known crackling issue) and they replaced the ear pieces (but not the case) without question or hesitation.
I was in basically the exact same position a month ago (pros bought launch week, very out of warranty, known crackling issue) and they replaced the ear pieces (but not the case) without question or hesitation.