I'm just going to drop these here: Famous Passenger Mounts obtained in-game
At the time costed you your arm and legs or a trip to Susan
Absolutely nightmarish to afford or you could just ask Susan for a loan
Pretty expensive at the time, didn't so much warrant a trip to the Bank of Susan though

Watch this "Marriage 2 person Mount" cost 10 million gil. If overmelding crafting/gathering gear didn't bankrupt you, or Novus, then I'm sure these 2 seater mounts being introduced will. There's no way they're going to be just handed out