As you are agreeing with your comments, acquisition cost is not the sole metrics in comparing across platforms. There are other important considerations such as sustainability, serviceability, parts availability, support services, upgrade pathways et al. as evident from the Malaysian experience making acquisition decisions on cost is short sighted and runs counter to a sustainable value proposition.
US could keep producing parts for F-18 to make sure its maintenance cost low, so does China, but USSR can't as it falls. That's why I said it's not a fair comparison in the first place since it's comparing the cost produced from China and the US, not a regime that no longer exists.
I disagree with the general argument of comparability on the basis of mission sets as they are too broad in nature. Based on mission set, I can make the argument that a B-25 and a F-117 is comparable because both are aerial platforms for delivering bombs. In a J-20 vs F-22 conversation, there are many capabilities that are classified and unknown. In the case of the J-20 we hardly know anything about its capabilities. How on earth can you make an argument that they are comparable? What is your basis? You need to make your case based on facts, not opinion.
Of course, you can argue B-25 and F-117 are comparable, and they do in a certain level, but when the conditions of a mission getting more and more specific, like to get around a 80-90s Soviet air defense system than B-25 will no longer fit the bill. Continue this process for a few rounds, you will find certain weapons that were used to conduct comparable missions or server similar roles by different countries, and those weapons are comparable.
I can give you an example of this, RQ-9 Reaper and Wing Loong are usually be considered as comparable, as their characteristics are all very close to each other, many countries have adopted either system. But can people like us, without knowing their specific parameters, still get this conclusion? Of course, based on their role and performance. Of course, we might not able to tell how much Wing Loong 2 is better than Wing Loong 1, but with more and more results come out we might.
The method I'm using here is not based on my opinion, it's base on the fact, and this kind of method has been wildly used in almost all subjects, math, physics, engineering, etc. If I remembered correctly, it's called 'Induction'. People always use this method to find out what's inside a black box system and evaluate its performance and functionality without knowing what's inside.
One more thing I want to stress here, I'm not trying to say which one is better between RQ-9 and Wing Loong, I'm just saying giving the fact that they are conducting a similar role and mission. We could say, to achieve a similar mission, the US needs to spend X times more cost (assuming RQ-9 is more expensive than Wing Loong, which I think it is) than Chinese, and X could be something like, weapon price ratio * weapon unit ratio used in this mission. You can add the operational cost and other facts to the equations, it will be more completed, but you will get a better comparison for sure.