What does it cost to craft a Hell-knight plate with “Easily Worked” steel?

I have problems calculating the costs for a Hell-knight plate which is crafted based upon the Pathfinder Unchained Rules and using a special raw material (Easily Worked steel).

A Hell-knight plate costs 2000 gp off the shelf, the weight is 50 pounds.

The Unchained Rules state, that you have to “acquire raw materials whose value is equal to 1/4 the cost of the item or items you wish to craft”, in this case 500 gp.

The price per pound for Easily Worked steel is given in the table “Special Raw Material Costs”: 8 gp for use as trade good, or 4 gp for use in crafting.

Following the line of reasoning provided in another answer on this platform regarding the use of special raw materials, one can apply the 4 gp/pound as price for the acquisition of the needed special raw material.

As the armor weighs 50 pounds, this would result in (special) raw material costs of 200 gp. But this is much less than the costs for “regular” raw material (500 gp). I would assume, that using higher quality raw material would result in higher costs.

What is the correct way to calculate the costs using “Easily Worked” steel?