What I'm talking about is the statement you made, "Is that a price we should be paying an Eredivisie team for a CB, probably not." Which is based on what? Nothing really, it's just an arbitrary opinion. The only thing that is going into that opinion is the nationality of a league, compared to the detailed analysis a recruitment team can make.
As with any signing in football, the ends justify the means. If he performs as one of the best CBs in the league and wins a world cup in the season after we buy him, then most definitely yes, it was a price that we should have paid an Eredivisie side for a CB. That seems fairly intuitive to me.
I don't think the Malacia point or the point about wider PL valuations is especially relevant to the point about Martinez. It's obvious that on average PL players cost more. It's obvious Malacia cost a lot less. Does it matter to whether the Martinez valuation was good? Not for me. It's an individual deal and they always have their own details making up the valuation.