Finding sleeves for 5x4 cards is almost impossible. But I may have stumbled onto an alternative....
They are slightly larger than a character card, but the closest I could find; one could slip a Character sized card (or Endgame card) into one of these, probably trimming excess BEFORE doing so. Perhaps there are other worldwide outlets for these sleeves sold by Artfire . In the meantime, I'm still searching for good alternatives if not an exact fit.