We've wasted plenty of big money on overseas signings. Andrade, Tiago, Poulsen, Diego, Krasic and Elia are the main ones.
There is no hard and fast rule, you buy players to suit your team. It's no surprise how our team has shaped up with our model, but maybe we could do with a few different elements. I don't suppose if we signed Benatia, Iturbe, Keita and Immobile there would be any real complaints. The complaints would only come if any of those players flopped, and how much money we wasted etc.