Some tackle shops do stock spare reel parts. It's the kind of thing to call and ask about. This seems to be more common with saltwater shops in my experience, but I'm sure that some bass only shops stock spare reel parts as well.

If you want to sit on your butt at home and have it delivered (my preferred method lol) you can call Shimano at 1-877-577-0600 and order any spare part you need.