How do Server Economies differ so greatly, especially Legacy vs. Non-Legacy?

[Morningstar1337]

I think you just answered your own question with this, people are greedy and greedy people (especially a certain group of spambots) tend to overprice stuff, and by definition, Non-Legacy servers are likely to have less veteran crafters crafting and selling their stuff. Supply and Demand comes into play here. Less veteran crafters means less competition which then means higher prices.

This might even apply to the non-crafted stuff like dungeon minions as there probably would be more players on a legacy server then non-legacy (Balmung being an extreme case)