In the mechanical keyboard worlds, aside from different type of keycaps, there are also artisan keys. These are individual key, usually used as Esc key, that are hand crafted and sculpted by artist, hence the name artisan. Currently there are many artisans, most of them hang around in Geekhack's Making Things Together forum.
Two of the most famous are Clack Factory and Bro Caps. The keys they made are beautiful
and is widely sought after. However, these keys are not cheap. Imagine a Clack Factory key now sells for around US$200 in eBay for a single color Clack. A bi-color Clack can go up to US$400 - the reasons is because to cast two different plastic together is very complex. A tri-color Clack could be selling at US$1,000!
One of the reasons for their expensive price is that these are hand sculpted and as such quantities are limited. And usually, the artisans sell them by doing ballot or first come first serve email entries. Getting one of them is almost like winning a lottery. For those that missed out have no choice
but to buy from eBay.
While I was lucky enough to own a few which I won at retail price, I'll never understand why people would pay such high value to acquire them. There is another collector in Malaysia that have been acquiring like mad. I can't imaging the amount of Ringgit he must have spent.