Yamabuki is the yellow gold flower ( I have a bunch growing in my japanese gareden) that the color of the koi reminds the japanese of , hence the name Yamabuki Ogon.....
Maurice already mentioned in the UK has done a fantastic job of gathering up some japanese brood stock and going into production for domestics there.
Here in the U.S.A we are very fortunate indeed to also have some first class
"domestics" available.
and there are other countries who breed koi and export them. malasia, Israel
Japanese koi are still considered the standard but as suggested the more you learn and can select koi objectively the more you can appreciate those produced here at home.
Back when I was in college the advertising course prof lectured us on a marketing ploy by salmon canners who were trying to break into the alaska sockeye market. People accepted the red meat as standard and pink or white as something wrong till one brilliant soul decided to lable thier cans "guaranteed not to turn red in the can"...suggesting something may be wrong with the processing. I say all this because many car companies today compare their product against the known standard for price and features. So much les$ than toyota, mercedes benz etc....In other words it always comes back to knowing a product and it's relative worth and that comes from knowledge.......