Hi Mitch,
Yes, there is no price for koi only what some one is willing to sell for and what someone is willing to pay. But there is real value if you know all the grades of koi and what makes one koi 'worth the asking price' and one not.
The show is fundamental in setting both price and value. Even one who swears never to show a koi and is even anti-show , benefits DIRECTLY from the show and its demand for ever better fish. The culls of that effort are what non show are offered.
The modern goshiki is from the same complex of many of the modern goromo. That is why they are called generally goromo class. These are all a mixture of kohaku and the old asagi ( asagi goromo) gene. fifteen years ago there was a goshiki ( black based karasu goi gene) and a ai goromo ( a kohaku with 'asagi bleeding thru!') . Today there is the kawari version of goshiki, the modern version of goshiki and the modern and old versions of ai goromo. That fish I posted earlier., by the way is neither an ai goromo OR goshiki! It is however from the same modern complex- can you put a name to it?
Most beginners are blown away by the white of goromo/modern goshiki. This is genetic link shiro ground similar to the shiro ground on purple based beni kohaku. The hard white can carry a fish for a while in its young life. But the tendency for the reticulation of asagi will quickly overwhile most of these fish. In otherwords, they get too messy and dark.
Here's a shot of a high class ai goromo of kohaku grade quality- Personally I like the reticulation lighter than this but this one ain't bad!