1x Earth Crystal = 41 gil (500gil/12)
2x Cotton Cloth = 960 gil (480gil*2)
2x Cotton Thread = 300 gil
(150gil*2)
Therefore:
3,903 gil will make a single stack, Assuming there are no breaks.
Crafting Fee of 25% = 975
Plus the listing cost on the AH, which is between 230 and 450 (Jeuno-> Al Zahbi)
HQ will reduce the costs further.
4,878 for a stack is the rough costing, including the small fee for crafting it.
This might seem acceptable for most, so why the additional 1-2k.
To get 40 levels in this craft takes time and money. (As does any craft)
Before you complain of either the price or undercutting, think about the time and money spent to get this far.
If you really don't like the price, go level the craft up, giving you the opportunity to create this yourself.
Making ninja tools is by far a good way to make adequete amounts of gil at a consistant basis. Combining Cloth with Alchemy one can fund their ninja with tools and be rather powerul with ninjutsu
Stop trying to raise prices up over 7k/stack, these are not worth that, and are a lot cheaper to make. No one is going to buy them for such a high price.