There are a few videos on YouTube that are very interesting and helpful in how to choose an inexpensive small koi that will likely be a beautiful adult. So for a hundred bucks...in a few years, you could have 12 to 15 nice specimens.
One thing I learned from youtube, is to not go for the brightest colored one, cause (they say) the color has already reached its best, leaving no room for improvement.
I've always chose the brightest!...then again it depends on what one is after, cause take the Yamabuki Ogon for example, they advise to choose a pale colored fish, so that in time as it matures it won't turn orange instead of yellow, but I don't mind a deeper orange tone on my fish...so like I said, unless one wants to show his fish, it doesn't always matter ...but to discard a fish because the color is pale is something I now know not to do