Recently I heard a news said that Zlatan Ibrahimovic shirt sales has given Man United profit £76 millions 
The best part is. it just happened for one week, well thats very amazing imo. So, Man United just need ~£30 millions more to sign Pogba, or it would be better if the money used to buy few good players instead of the Frenchman.
They have sell £76M worth of shirt , they didn't get the full profit , but still there gonna be a lot of profit in just ONE week. That's exactly why sometimes a club spend a lot money on player.They not just buying the player talent, they are actually buy the player popularity too. No doubt Paul Pogba are really famous for many football fans , imagine how many kids will buy his Manchester United shirt. Really smart business from Mourinho , this is how special he is. The best part is. it just happened for one week, well thats very amazing imo. So, Man United just need ~£30 millions more to sign Pogba, or it would be better if the money used to buy few good players instead of the Frenchman. 
Picture source : Bleacher Report UK facebook
Man utd is the luckiest club to get Zlatan with free transfer.
They are indeed. Also the Pogba transfer will also be profitable because they will be looking to make him one of the most popular players in Europe. He's young, so imagine where he is at 28 - 30 years old. All the Pogba shirts sold will total way more than the transfer fee paid for him.