The unlicensed stuff market really only exists to those that are fans of it; collectors of normal stuff think it's worthless because it's "pirated" or is a shitty game. Those types will either price it too low or insanely high.
It's one of the few genres where the price doesn't fluctuate too much, and it usually boils down to what a game is worth to you. The majority of these games are sold for pennies on the dollar in places where primarily exist. I don't know of any bastion of games where Earthbound or Kizuna Encounter are sold on open air markets for $3 USD.
I've got some things that I paid high dollar for that I couldn't sell for the same amount if my life depended on it, but they were worth it to me.