I remember a patch note that made event items increase in (ingame) price with age. I know ingame price is worthless but I’m interested in the formula.
As more and more people play a game, the demand for a specific thing will grow
And because it’s unobtainable, the supply never grows
Also, once someone acquires such a valuable item, more often than not it isn’t for its trading value, but rather for its status, which means the supply will actually diminish