Like every other guild, prices vary on a day to day basis, so I think it would be better to put a price range next to each item, rather than a specific price. For instance, at this particular npc I've seen Noble Lady at 2100g, and I've seen it at 6k.
My experience is the NPC has 100 Cobalt Jellyfish to sell each day. I found her price to be 32/each. I suspect Windy fame affects the price. I have level 9 fame in Windy. This occurred twice.
UPDATE: Just went back to buy again and was able to 150 at 23/each.
IB
Edited, Sep 20th 2006 at 8:16pm EDT by IBHalliwell
It's a guild merchant, but doesn't operate at the same hours as the fishing guild, it's starting to seem like it doesn't close, yet it wont restock items either. Very wierd.