Ship cost is determined by ship systems (i.e. armament and sensors) much more than by steel used.
Some expression of cost per ton can only be correct a) if it starts from total ship cost and then devides by tonnage for an 'fictitious' cost per ton (after all, it is not the price of the steel amnd building, but also weapons and sensors), or b) it is the real cost of steel and building i.e. the price of the ship without 'government furnished equipment' i.e. weapons and sensors'.
Admiral or no admiral, the above quite is ambigious in that it remains unclear how that $500k per ton was arrived at, what it actually represents.
The inherent trouble with a big series of ships in a short time is that at some point (around 2040-2050, unless ships are used longer than 30 years, which would limit their usefulness/effectiveness ), PLAN again will face block-obsolescense.
056: over 20 commissioned between 2013 and 2016
054a: over 20 commissioned between 2008 and 2016 (not counting the pair of 054)
052C: 6 commissiones 2005-2015 (of which 4 in 2013-2015)
052D: 12 commissioned or commissioning between 2014 and 2019
[given the average current build rate of 3 per year, to get to 30 or more 052D, you take (30-12)/3= 6 more years of production i.e. production through 2025]
PLAN has been rapidly building 056's, 054a's and 052C/D's, so when it is time to start looking at replacement, it will again have to replace many vessels in a relatively short time span.
By comparison, the USN has been building ABs slowly but steadily and in different versions since 1989. Including phased modernizations of older vessels, these will also gradually be phased out and replaced in the future.
Source:
https://warisboring.com/u-s-navy-packs-firepower-into-shrinking-sub-fleet-50c72bd38b83#.qc6ijqyth