The answer you are quoting, while not worded as such, is not philosophical. It is an actual description of how pricing works, which is not (directly) determined by the cost of inputs.
The i7 laptop does not cost more than the i3 laptop due to the cost of the processors, rather that demand is increased through the relative increase in performance. The demand (and supply) determin price. Cost of inputs affects prices indirectly, for sure. It informs the production decision, that is: Good A would cost me X to produce, and demand price Y, if Y > X then I might enter the market, but the act of my entering the market shifts the supply of A thus affecting price. So while costs of inputs inform product decisions, which in turn can affect price, there is not a direct cause and effect relationship between cost of inputs and price.
Is it better than the iDSD? That's not a question that can be answered. Does it suit you more? Maybe. With some EQ I'd wager they could sound indiscernbile from one another (in blind testing) but they are also very different goods. Is it worth the price difference to you? Probably not, I personally wouldn't buy either of them. I am considering an AK300, but for my own reasons, it's also too expensive, in my estimation - that is, to me.
The real answer to your question is that audiophiles are willing to pay $3,800 for the AK380.