Every player will sell, you just may need to offer a few out for very little. The only problem you might have is players that have only just signed for your club, other teams may be reluctant to bid for them, usually due to them having massive wage demands especially as you are Man City.. However clubs will only bid for your players if they need them, i.e at the start of the game Chelsea & Liverpool will buy pretty much any striker you offer out (as long as you are a good prem team and the striker is decent) as they both need a striker.
As you don't really need the money, attempt player-exchanges, they are a great way of getting good players for free and in return making a nice saving through wages.