Koi don't school together. They go about and do their own thing. Yes, they swim together, but most of the time you will find them off doing their own thing.
Cichlids and koi don't often mix well together because the cichlid eventually get the upper hand.
Not to mention, koi need extremely cleaner water paramaters than cichlids, cats, and goldfish. It's very possible you may end up having a koi with ulcers or fin rot.
Personally, I wouldn't pay more than $200.
I have over 100 koi, and I've paid $400 for an individual import.