I sold the first Vitality V materia on my server for about 6 million gil back in October. To be honest, I didn't think anyone would buy it. There weren't any others up. Tier V materia was much rarer then (only came from spiritbonding the i160 bodies), instead of basically being handed out now. So I just picked a price that seemed high enough to represent the incredible rarity of the materia, combined with me remembering how I sold my first vitality iv materia in 2.x for like 500k, and yet sane enough that someone with gil to burn might eventually get it and went with that. I was actually very surprised when I came back and found 6 million on my retainer from it.