It's not just per unit cost, of course. It's also a matter of how many can you build over what time with what available resources, which would not be limited to just money.
By China's own admission and timeline, this modernization will not be achieved until 2035. And while the Chinese military is on the path to that, a war may start in the next few years, a point which was actually part of the original discussion: "And it would be bad strategy to shut down production of such a cheap and reliable figher when things could go tits up in the next four years".
While I don't disagree that the end goal of China's military modernization is victory through technology, strength of numbers will not ever disappear from such a calculus, including during a war when supplies dwindle and ease of manufacturing becomes more and more relevant. Nobody is trying to insinuate the human meat waves of the Korean War here, but that doesn't mean it won't be a numbers game, regardless of the technological balance on either side.