I wouldn't take anything less than £25m for Nani. Yeah, he's going through a poor spell, and we don't know if his game will ever return (which is shocking to say, considering his age), but selling him for £20m could look utterly stupid if he does hit his peak.
Similar for Vidic, £25m for him. If he gets back fit he's one of the top defenders in the world. Sadly, we've got neither Vidic nor the £25m at the moment, and with his increasing age, I'm not sure we ever will.
Anderson could go for me, but again, I wouldn't want us taking anything less than £15m. He is still quite young, we don't know what the future has for him.
Get rid of Macheda. Just, get rid. Throw his bus fare in. There is absolutely no purpose for him in this squad.
Sadly I know we wouldn't get anything like the three fees above if we were to sell them.