I pretty much agree with that, except to say I think he could have bought several centre backs that wouldn't have improved his team at all. VVD is clearly very very good.
You fundamentally fail to understand the transfer market if you're asking questions like that. VVD might only need to be 5% better than Dunk to command 3 times as much money because in any given game, that extra 5% might be all it takes to win 1-0 rather than draw 1-1. Football is about fine...
Slightly controversial I know, but I think Dunk is one player we should encourage to leave. Not that I want him to go of course, but that fella is destined for bigger things, notably England caps. He is tailor made for Arsenal who need to rebuild, and they'd pay a huge fee for him. If not...