For me it's just easier to change out the whole reel rather than change just the spool. Not that I don't have reels with extra spools too, but if a spool for one reel cost as much as what I can get another whole reel for, guess what I'm going to do.
I recently picked this reel up at a yard sale
It's an LLBean "Double LL" made by STH
Good reel cheap
(probably should have cleaned it before taking a picture