Okay, let's consider the market in the City of Brass for quintuple sequences of enhancement Wishes!

Noble Efreet are not exactly rare, in the City of Brass.  The place doesn't run much in the way of censuses, but there can't realistically be less than twenty thousand noble Efreet here, all of whom can cast 1 Wish per day.

This means there are many, many more noble Efreet than there are travelers with Wish diamonds to convert to Wishes!  The process doesn't take long and doesn't exhaust a noble Efreet, either!  And if you were very naive about how markets here operate, you might reason -

The City of Brass's price of converting a Wish diamond to a Wish should collapse to a small service charge, about what you'd pay for a few minutes of a noble Efreet's time for any other service; modulo transaction costs that both parties are incentivized to keep small.

(At least, assuming there's no such thing as a 'premium Wish' that fewer noble Efreet can offer.)

Yes, if you were very naive about how markets work, you might think that!  But naturally the City of Brass has legislated rules about minimum Wish prices - which, of course, it is illegal to explicitly tell travelers!

...then obviously you're going to have more and more entrants into the Wish-diamond-to-Wish conversion market, until all of the excess profit from this artificially high regulated price has been dissipated in marketing expenses and idle labor.  You'll get noble Efreet shops advertising Wishes on every corner of the City of Brass, as they all compete to be the shop a traveler chooses, to buy this legally overpriced service that 20,000 competitors in the city could also offer.

This artificially high price will also have the further result that fewer outside purchasers will come to the City of Brass.

Thus, the net value captured by Efreet and not dissipated in competing for overpriced transactions will be less.

Why would anyone do that to themselves?!

Because the travelers have to spend more to buy Wish-castings, and if they're losing, the Efreet must be winning!

Huh.  What's the average Intelligence and Wisdom of Efreet?

12 INT and 14 WIS.  Why do you ask?

No reason.  Anyway, dath ilan accepts the City of Brass's correction: standard economics does indeed fail to describe how trades in the City of Brass work.

Standard economics, ha!  Dath ilan is just naive about how markets work in real life!

...if you consider Lawful Evil aliens with INT 12 / WIS 14 to be 'real life', then yes, standard economic models from dath ilan do not well describe what happens when such aliens in 'real life' try to operate what they imagine to be a 'market'.

Anyways, the City of Brass was saying something about its 'market' for sequences of 5 enhancement Wishes?

Right!  Now, while it's pretty rare on any given planet for somebody to assemble 5 Wish diamonds that they want to convert to a +5 abilitystat increase, that's when you're considering just one planet.  If you consider all the planets across all the planes, that have advanced to the point of anybody there having Plane Shift, that's more like 10 parties per year that come into the City of Brass with 5 Wish diamonds that they want to convert to 5 Wishes!

And this service is overpriced as a matter of regulation, so there's many groups of 5 noble Efreet vying to persuade travelers to buy 5 Wishes from them.  Correct?

Yep!  Though not to the same extent that every noble Efreeti you come across wants to sell you 1 Wish.

Are there... 5+6+6+6+3... at least 26 groups like that, in the City of Brass?

Yes, there are.

But you'd have to walk around quite a bit, passing many more shops looking to sell you one Wish conversion, and skipping any 5-noble-Efreet groups already marked as 'tried' by a nearby Arcane Mark from one of your companion groups.

You might, at some point, have to grit your teeth and start trying to pull together a new group of 5 noble Efreet who weren't already advertising that combined service, maybe get a 2-group willing to cooperate with a nearby 3-group.  Though this will be a lot more annoying, and run a much higher risk that this is externally visible.

If the natives combine information and figure out you were buying more than one quintuple series of Wishes, that is going to point a lot more interest in your direction, if anybody catches on that far.

The ideal and hoped-for outcome is that you went around visiting a lot of shops and swearing them to secrecy, and maybe the City of Brass can figure out that part; but they don't know all those negotiations concluded successfully; and the larger City just guesses that this weird party was trying to negotiate too hard, or had some weird extra secret condition that most noble Efreet groups turned down.

This is about how Carissa expected everything to work. The important thing is that they're not weirder than other things that happen around here frequently, and that they can get their delicious delicious Wishes.

Oh, they're definitely not weirder than the weirdest thing to happen in the City of Brass in the last week.  So long as nobody actually infers that they have unlimited Wish diamonds.

- does Carissa want an Armillary Amulet equivalent that somehow provides a +7 bonus to Spellcraft instead of a mere +5?  It'd be only the equivalent of 20,000gp, and she could try paying in spellsilver to make the real price to them be a quarter of that, maybe, if she's good at haggling.

- yes, yes she does, and she's not even all that interested in saving Keltham money. She has yet to run across a problem other than imitating Hell-forged artifact headbands that seemed to require more spellcraft than she already has - the trickiest parts of Keltham's simulator lie elsewhere - but that doesn't mean she doesn't want MORE.

Well, Keltham hasn't seemed all that interested in saving Keltham money either!  But Carissa doesn't have an infinite quantity of spending money with her on this trip, unless you count unlimited Wish diamonds that can only be spent if conditions of secrecy can be created around that and you know what a noble Efreeti plans to do with them, and you may need that money for other things.

Like an IOUN STONE.  Does Carissa Sevar want an IOUN STONE, a vibrant purple prism that stores up to 3 total circles of spells?  Nobody in Golarion has been able to make an IOUN STONE for a long long time, but maybe they just didn't have enough Spellcraft and weren't soon to be INT 29 and didn't have a magical simulator of magic physics and weren't trying hard enough!  Also her cult members would probably be pretty impressed if she walked in with an IOUN STONE orbiting her, at least those of them who knew what an IOUN STONE was.

- okay yeah maybe she kind of wants one of those too. 

She could totally figure out the lost Azlanti art of ioun stone making if she wasn't going to die in a month.

The proprietor of this store is a noble Efreeti who stands tall even for a noble, currently bargaining with an even larger Brutalis devil over a heavily magicked sword that Carissa couldn't lift with a Bull's Strength.

Serving as store assistant is an Azer - a brass-skinned dwarfoid native to Elemental Fire, whose hair and beard trail off into solid flame.  Almost all of Azerkind are enslaved by the Efreet, for the Azer's citadels were distant and had poor relations with one another, so that the Efreet armies could fall on their cities one by one and enslave them, without the next city becoming any the wiser.

The Azer assistant will inform Carissa that the price of the Ioun Stone proudly displayed in the store's window is -

- well, Carissa can either blow her whole remaining budget on that one Ioun Stone.  Or she could try to meet Keltham's conditions of secrecy and known use, to trade a Wish diamond.

....she should in fact do this AFTER she is smarter and not before. If she feels on some level like her greater Wisdom will lead her to not buy the ioun stone, that's because she actually shouldn't.

And if she should, she will. 

Before Carissa can go, the Azer will inform her in a low confidential voice that if the Ioun Stone orbiting in the store display caught her eye, there's an Orange Prism Ioun Stone that can be brought forth for the truly discriminating buyer.  It would increase the power of all her spells by about half a caster circle, including when it came to determining what sort of spells she can Permanency.

Well, how does this shop feel about Keltham's confidentiality agreement.

The huge malik (noble efreeti) and the huger devil don't seem to be coming to terms on the enormous +2 keen wounding sword.

The giant devil, of dull-golden hide, whose head and shoulders are both crowned and crested with many horns, turns away finally from the bargaining counter.

"He overcharges, even more than do most of his kind," the devil says in Infernal to Carissa Sevar.  "It seems he has some prejudice against Hell and Hell's."

The devil's voice sounds exactly like Carissa's father.

And Carissa feels a surge of hatred towards those awful price-gouging lol no Carissa has a Mind Blank up.