For the figures mentioned on Morata I think he's way too expensive to be considered a valuable solution. Also, he's not an ideal Mandzu replacement as he is more of a CF then a LW / LF.
On the contrary, Martial is mainly a LW / LF but capable of playing CF.
Although we have a special relationship with Morata, and the players desire could help us get him, I don't think he's remotely close to a valuation of €70m! Even with a €15m loan and €45m buyout clause.
If we can get Martial for €50m, this is a no brainer: better value for money and a player who fits the position perfectly.