I haven't seen anything to suggest that clubs like Madrid are interested in Vidal though. Vidal mentioned that he heard rumours of Madrid, but I had heard nothing of their interest before this. They'll be completely abusing their financial power if they sign Vidal in the same season they bought Kroos and Rodriguez. That being said, I'd probably accept £40m + Nani, it's moreso the people trying to say he's worth £50m+ which I don't believe he is. Your point on top cms not wishing to move in their primes is a good one and if players like Iniesta had moved in their prime, it probably would have been for north of £70m. Still, Iniesta, like Zidane and Kaka was a more attacking cm and they do tend to attract more. Even at his prime, I'd have been surprised if Schweinsteiger sold for too much more than £40m and he's the most similar to Vidal out of the players you've mentioned. I don't think Vidal will ever do enough to justify £50m, for that, a player really should be able to make a massive difference in terms of goals and assist output and while he'll probably improve us in that respect, I'd expect the numbers to be at most around 15 goals and 15 assists per season. I want Vidal, but just over £40m would definitely be the maximum for me, £50m+ is far too expensive as far as I'm concerned.