Whether you like it or not, 50 million GBP buys you an 19 year old Raheem Sterling or an untested Martial these days. The amount of money elite clubs are earning way exceed transfer inflation, so these sorts of fee's will continue until revenues start to decrease.
Beyond Messi and Ronaldo, Neymar, Pogba and Bale are the 3 players set to fight it out for BPITW. And so to acquire any will require you to break the world transfer record.
We are one of the top revenue generating and profitable clubs in world football: Ive been frustrated for years watching Barcelona, Madrid and Manchester City pay market rates for top shelf talent whilst we have fuddled around in the upper middle of the market.
Appointing Jose Mourinho was a statement that the club wanted to acquire the best employee for every position in the club. It costs what it costs.
Mourinho's first task is to get back to the top of the tree. Once he has done that, and gained confidence and momentum, he can start to phase through club youth players.