Lore question about Rowena's HoS

Just cause they aren't available to you doesn't mean they aren't getting sold. Potions for example I can see being sold to high class gladiator and Adventurer teams or perhaps high class knights in Ishgard who demand the very best quality for their use. Potions are also utilised in non combat situations like someone taking an intelligence potion to help them while studying or a strength potion to add with physical feats. Or a stamina potion so they can last longer during physical exertion.....

Anyway the point being that Rowena has a wide range of customers and many look for exclusive items.

Just realized the abbreviation for her operation makes it sound like she's running a brothel.
Which, knowing her...

One question for you:

who do you think is supplying all those NPC vendors you encounter throughout the world?

Rowena does have a bit of an altruistic streak. Putting some relic weapon / anima weapon quest stuff under the spoiler tag here...

Once upon a time, Rowena found herself in debt to a bad person. She was trying to pay it off, but Gerolt got a wind that she was going to be assassinated, and stole her stockpiled fortune to pay off the loan shark. This is the source of their enmity toward one another. (They were, uh, married at the time. I think they still are.) It left her without a gil to her name. Gerolt has been trying to pay her back, kettle by kettle.

As part of her empire building, Rowena vowed that no other woman would find herself in that situation, so she will buy out the debts of destitute women and give them the opportunity to earn an honest living in the HoS. This is why all sales persons in HoS are women.

As to what she does with it - yeah. Sells stuff to the elite weirdos of Ul'dah and trades across the globe. Where do you think Gegeruju got all those Shisui outfits from? Rowena likely put him in touch with a Kugane merchant and brokered a nice fat trade.

Guy's its obvious what she is doing, she'll making and gearing an army. She'll soon conquer the world, she'll be the true and final boss in the game.

This is a secret but in fact she's the sister of Julyan Manderville :-D