When I first started, I saw Cloud on sale for 1mil coins, so I assumed they would all be a horrendous grind to get. Lightning and Firion are similar, asking you to go against an NPC with impossible rules for a tiny chance at them. But then I see Squall is as simple as beating each NPC once (which takes a similar amount of time as grinding for a single card, really), and Shantotto (as easy as participating in a tournament or two).
Now, these seem like wildly different difficulties in hunting. Are some cards simply really easy to get, while some really difficult? Or are they easier to get than they look?