Dear SE, to kill some time...

[darkstarpoet1]

You're right, but only when it comes to ACTUAL money. Using Gil, a virtual currency in a virtual world, doesn't fall into that.

As far as rare and powerful cards, you can make a four-fold system. When you defeat a powerful NM, like Ifrit for example, you can get his card. With his card, you can:

-Use it in a game of Triple Triad
-Trade it for a unique Ifrit item (Weapon)
-Refine it into a powerful crafting item. A Tier V materia of your choosing.

i could still see some government agency try to ban it because there is a gil selling market so they'd want to consider in game currency the same as poker chips. i know it sounds far fetched, but never put anything past the government.