City splashed out £32.5million on Real Madrid forward Robinho on Monday, after being taken over by a group of Arabians.
Cook said: “Never say never in this game. It changes on a daily basis.
“Just two years ago this club was looking at a very different type of player. Now, nothing is going to stop us.
“When you are moving the club forward you stop at nothing to get some of the best players.
“It’s very competitive but you have to rely on the manager’s judgement and the player’s desire to play for the club.
“We are entering a new era. The fans are going to see the best players in the world. That is what they are looking forward to the most.”
