The cost of ~1 billion pounds for the Daring includes R&D costs. At then currency exchange rates, that's about $1.6 billion. I have not located unit costs for this ship. Given that it's a 6-unit build, the R&D costs will certainly occupy a large percentage of this figure. The costs given for the KDX-3 are unit costs, not project costs (project cost being unit cost + R&D per capita). Also, it is very important to note that the KDX-3 literally uses no new technology, and this is a frequently given reason as to why it's cheaper compared to other ships. All systems were bought from other countries or were already present on the KDX-2 class. Similarly for the Kongo; I think the only new system for the Kongo was the ECM. I certainly don't deny that there is a country of origin discount, and as large shipbuilders Korea and China would accrue savings from both efficiency and scale, and in the case of China, labor as well. But we should definitely not forget that besides the weapons systems, almost all (if not ALL) of the electronics on the 055 are literally brand new. If as I suspect the AESA on the 055 has separated the volume search and fire control functions, it definitely is a new variant of 346 or even new radar altogether. On top of that is the integration of sensors into the hull and mast, which as I mentioned has quadrupled the costs for several of the sensors/emitters. The electronics make up the lion's share of a warship's cost, which is why $923 million for a 055 seems low to me. If this number is the unit cost not including R&D costs, it would be somewhat more within the realm of possibility IMO.
Yes, I can appreciate the Daring's cost includes R&D spread across only six hulls, and that's why I also listed the Hobart class which fields all existing systems (therefore R&D costs being substantially lower) yet costs a significant amount despite only being a 7000 ton ship (I think the latest audit says $9 billion for three ships)
Then, looking at costs of recent Flight IIA Burkes (using all mature systems) they tend to cost in the ballpark of $1.4-1.5 billion, and looking at the difference in costs between a Flight IIA Burke, a Hobart and a Sejong, despite their wide range of size and different capability yet having similar sensors and subsystems (all mature variants of one another or mature systems of the same kind), the fact that the costs can vary so much indicates to me that there are significant factors which can accrue savings and/or cause extenuating costs.
How this applies for the 055's supposed cost, imo, is that looking at the range of costs of those destroyers and the range of size and different capability of those destroyers, yet all fielding mature systems of the same kind, makes me 055 could have quite an even lower cost if it used all mature systems, and that it is only through adding the extra cost of new electronics and those new subsystems that takes it to the supposed $923 million mark to begin with.