For reasons unknown, looks like two of the infamously expensive Pony Canyon "Nintendo Sound Series" discs are going for pretty wild prices on YJA!
Mario Kart 64 | currently going for 27,778 yen
Diddy Kong Racing | currently going for 25,000 yen
Astonishingly, DKR is in rough shape. Both have no obis or stickers based on what we can see in the pictures.
As it goes now, I believe these are the rarest, most sought after of the "series" with Zelda OOT being the least sought. If I ever see a Banjo-Kazooie, I'd estimate that one would be the rarest.