IMHO this thread is not pointless, and afterwards some good posts have been written.
However, if "numbers" are to be analysed it must be done case by case and bearing in mind other relevant factors such as age, and remaining contract.
For instance Crouch was a great buy, because he was bought for a reasonable sum, he has done his job for us, and if he's sold now, it would be more expensive than when we bought him.
Morientes is more tricky, because a player of 28 years will be always more valued than a player of 30.
I think that every case must be analysed individually and THEN jump into conclussions rather than getting all the raw figures and jump in to conclussions.