Years ago we had a friend who lived on our couch and played Second Life all day (we used to tease him that he didn't have a First Life.) One thing I saw that astonished me was that someone had written a tool that could create mirror images of a model (reverse one axis.) They were charging people per-use to create flipped duplicates of models they already had. (It doesn't need to be said but I can't help it: this is a function that would be a drop-down menu item in e.g. Blender!) I tried to explain him about artificial scarcity and Turing's Universal Machine, but he acted as though I was the one who didn't get it. (He's right, I don't.)

Yes, since at least 1977!

Oubliette, a PLATO graphical (well lines :)) multiplayer RPG had a secondary market where people would in-game items for real-world cash.