One think to consider is that I believe Marotta was willing to pay till 30M to keep Morata.
That would make an effective cost of 60M, obviously, because we would give up getting 30M for him.
So when it comes to the fees, the board is actually willing to spend Morata + 30M for Higuain. When you look like this, it's not that crazy. Morata's wages would have to go pretty high too.