Manchester united budget was not a lot. The funds must be used wisely due to the FFP rules. I think that mason mount will need at least 60 millions and that means united has remaining amounts of money that can be used to buy onana from intermilan.
Manchester united has been putting mount and onana as its priority for the upcoming season. It's caused by MU really needs a new keeper to replace de gea.
I hope that manchester united's transfer will be going smoothly according to the plan.
I don't think Inter would accept 40 Million Euros to let Onana leave them because Inter is currently in similar situation like Manchester United where they don't have other good goalkeeper which can replace their main goalkeeper. Inter do have Samir Handanovic, but he's already old and can only play for few matches.
Inter will demand crazy amount money to Manchester United, it's better for Manchester United is looking a new goalkeeper in Championship league or other league 1 clubs.