Latex rubber is a natural material. It is the sap of a tree, most commonly the Amazonian rubber tree (Hevea brasiliensis). The bark of the tree is incised and allowed to bleed sap, which is then collected and processed into latex rubber, and optionally further into latex sheeting. Latex clothes are made either by using latex sheeting in combination with traditional dressmaking techniques adapted specifically to the material, or by using the latex in its liquid form to make moulded clothes.
Latex sheeting itself is not exactly cheap. And there's only a handful of companies worldwide that produce it, and even less that do so with a high standard of quality or ethical production methods. So the price per meter is in the range of a premium or luxury fabric.
Putting the price of the material aside, it's the process of making it into a garment that is so precious.
Because it's so unbelievably hard!
No wonder it's such a prevalent material in fetish clothing, one has to be downright perverse to put themselves through the ringer of making latex clothes. Never mind that it's all worth it in the end!
First, one must master pattern-cutting for extremely stretchy fabrics, which is in itself a notoriously difficult specialisation within dressmaking.
Then you have the challenge of adapting the existing techniques to a material which behaves like no other. Constructing a properly fitting rubber garment, that also fully utilises the unique body- sculpting and haptic advantages unique to latex is an art in itself.
And then, you get to the construction.
Latex clothes are not stitched the way other clothes are. Each seam is glued, in a chemical process that is actually more like welding. The molecules of the its surface are primed, treated and otherwise coaxed to create a new permanent chemical bond. This is all done by hand, in a process that is extremely complex and requires great manual dexterity.
It takes years to build the muscle memory necessary for gluing seams properly. It's much like learning to play an instrument.
And there is no school that can teach you. There is no place where one can receive formal training, and not many resources for learning how to do it. Historically, latex clothes have been very niche (at least until very recently when every bubble-gum celebrity and their mother got their stylist to buy them latex circle skirts). As such, the craft of how to make them has been passed on from one person to another much like other traditional crafts used to be in the past.
Except, you know, in this case the end goal was a very very shiny bum.
All of those elements make latex clothes a precious rarity and explain why they are coveted, and not so easy to come by.