how is this possible?

[scarebearz]

I'm sure it's dodgy, but going by the retainer names, I suspect it's a player (or several), rather than RMT.

The market on Odin stinks in many ways, a few buyers appear to spend 10's of millions per day on overpriced items/materia/minions, causing prices to be insane for some items. Not to manipulate the market, but just buy whatever they want, no matter the cost.