The problem with buying at NPC, is that you end up paying almost 150% of AH price, even with max fame, roughly 110k per stack of bullet pouches, and 40k wasted just because nobody is crafting is kinda silly when you can put the money towards leveling it yourself.
You don't really want to buy them in Nashmau. I went there to check the price on them and they are indeed bellow 90 each. Assuming that everybody has his/her tenshodo fame up to 4 (due to the utsusemi quest) the price on this is 67 each. I don't know if the price fluctuates like the guild merchants but they do have a limited amount of bullets, they don't even have a full 99 stack. That's why it's not even worth checking them and thus it makes getting each bullet at 90 gil with hero fame making a stack of pouches worth 106,920 plus the carnation, 720. Much more cheaper to buy from the auction house.
Merchants
Price: 58 ~ 436 gil
Name Location Type
Jirokichi Norg (I-8) Tenshodo Merchant
Olaf Metalworks (G-7) Standard Merchant
Shiny Teeth Rabao (F-6) Standard Merchant
Tsutsuroon Nashmau (G-7) Tenshodo Merchant
Before buying singles, you should really check the stack price. I've never seen these cheaper single rather than bought in bulk. And currently, on my server, you waste nearly 30k by buying singles.
Not exactly sure where Solarhawk is getting 110k per stack from NPC.
In Nashmau bullets can be as low as 58g, thus 5742g per stack of 99 (58 * 99). 5742g * 12 = 68904g, 12 for the number of stacks needed for a stack of pouches. Carnations are 60g in Jeuno, so 12 * 60 = 720. Combined total is 69624g, only 4.5kish more than most stacks (dependent of course on server).