We're talking about batting because you said leather armour was dirt cheap but used inaccurate numbers to come to that conclusion.

Batting does not affect the armour stats, so I don't know how adding it makes the price of leather armour any more "accurate"

Compared to other forms of armour, Leather is cheap.

A 40/40 shield costs 20,000 while a 5 piece suit of 40/40 leather armour costs 5,000

I think the idea people are missing is that the request wasn't for leather armor + batting to be equivalent to fieldplate, it was for leather armor + batting to be equivalent to greatrobes. So since greatrobes can be proofed, and batting is necessary for proofing leather armor, it needs to be included in the price calculations. And just going by the numbers I'm seeing here, it seems that leather armor with batting costs more overall than robes do, for a lower benefit.

Which commodities are used to make Greatrobes?

Leather + batting would be 100 silk and 15 leather.

90 comms for greatrobes, doesn't matter what they are. 90 cloth is common.

In case it hasn't been stated, just a little note.. I think robes can go over 60/60. My current robes are:

What the comms are matter a whole bunch.

90 clot or 90 bluetints or 90 steel, makes a big difference.

Hmm...that doesn't look quite right. You sure those aren't Splendor robes, or something else special? I've never seen anything over 65.

I'm sure. I got them from Flarya's shop when she was a Celestian.