How much would you actually pay for Tufan if he belonged to another club and had 3/4 years on his contract? Although I like him, personally, I wouldn't sign him at all but if I was attempting to be fair maybe 3.5m? so 2m euros for a player that wants to go, has struggled at times with consistency and is in and out of the team makes sense to me.
And a year left on his contract, which is the key thing.