What goes around
Water/liquid cooling always used to add quite significantly to the cost. Almost doubling the cost of a machine. Cray used to do the T3E in both water and air cooled versions for this reason. The water cooled version packed a lot more processors into the same cabinet footprint, and was the only way to get really big configurations. At the same time Thinking Machines made a big thing about the cost effectiveness of their air cooled designs. Considering the prevalence of water coolling for gaming machines at least some of the components should be pretty cheap now. But anything custom or low volume is going to be a problem.
The Cray 1 was also water cooled, but conventional cold plate. The Cray 2 was famous for being liquid immersion (in Freon) cooled. You had to drain the Freon out of the cabinet to perform any work on the machine. Cray's factory cooled a large pond outside the building with excess heat.