We just have to be really rude with Madrid, like all the club does when they are negociating with them. When they want a player, they usually get him. And they are the best at doing that.
Anyway, I don't understand two things. The first, why we didn't gave him a contract extension after our last title. Fergie should have done that, and Moyes unstead of signing Nani and Rooney should have extended him also.
And the second thing is that we're interested in Benzema, but we all know that Benzema will not leave Madrid. In general, Madrid offload his player to make the way for another. IF Aguero comes to Madrid, then Benzema will be free, but for the moment we just have to negotiate a good fee for De Gea and make sure we take one somebody we realy need like Varane or Carvajal, and maybe coming back in August (after an agreement with them) for Benzema.