Ilkay Gündogan isn't exactly the sitting midfielder we need. He is more of that dynamic box to box marvel who works very hard but isn't as good as Carrick as a CDM.
If we really do need a CDM, I'd go for one of Nigel de Jong(free), Grzegorz Krychowiak and Johannes Geis. They're exactly the kind of CDM's we need. And they aren't too expensive too.