Why you need extra retainers

[Gamer3427]

Here's the thing though: a lot of players will NOT look up where you can purchase mats from NPCs. If it's not available within a town vendor or their class' guild, they automatically assume you can't buy it from an NPC. I know quite a few people that will buy things from the residence districts' vendors and from beast tribe vendors and put those items immediately back on the MB at double or triple the price. And it sells. Quickly.

This. As an example, you can buy cinnabar for a measly 3 gil at the tradecraft vendor in any of the three city-states, as well as the vendor at the Alchemist guild. On the market however, NQ cinnabar sells for about 40 gil each, and while not selling quickly, does sell. People are lazy. Especially if they have a little excess gil from leveling another DoH or DoL. Rather than trying to find out where something is sold or obtained if they don't know, they'll just buy it off the MB without a second thought......

EDIT: I should say "on the market for my server" it sells for about 40 gil each....