A unique animal to the desert that has to be undisturbed to produce product X.
I'll just use ostriches here to give that thing a name, also because it's used a lot in ancient Arabic poetry and they lived in the desert. But you can change it to Griffins or whatever you want.
Also change the product. I'll just call it X. It can be gold, magical lighting gems, highly potent medicine...etc.
The basic premise is that as long as someone is willing to pay for it you can make a profit.
Like a lot of "luxury" items. To this day illegal pouching exists.
First of all the undisturbed part covers the question of breeding the thing.
Mostly a handwave but we breed camels, horses, goats, cows...etc...etc.
So the first reasonable step is to breed ostriches.
However they do not take kindly to that. Once in captivity they wither and die.
And those who survive produce a weaker version of the real thing.
So they need a lot of the open desert to produce strong X.
The second part is that they are very dangerous and can kill a man easily.
So people learned to hunt for X that is unguarded or something similar.
For example instead of going to the animal and taking X with a fight that will lose you the animal or a human, they just track it for miles and then capture X when it is unguarded.
And the whole trade is a thing that is passed down from family member to family member or from master to student.
Because the goal is to capture X that is natural in the wild without causing trouble.
You can also add a lot of other things.
For example X produces a natural toxic gas that is harmful in small doses.
But skilled hunters build an immunity to the thing by small exposure until they develop a physical sign that tells them the are immune to it.
This sign thing adds a unique appearance and seems cool. But also serves to actually show they are immune.
So maybe a blue or green nose? Maybe a large patch of dark skin on the cheek.
Something like that.
So the limitation of the animal with the danger of the product and the time limitation of production and training gives the whole trade certain limitations that makes it profitable to a small number of people but insures it stays small, so far, and limited in most ways.
That's all I can think of right now.