Making it work for ffp is a separate thing to the raw figures being below market value. If i buy something for a tenner then discover its worth £10k, im not going to happily sell it for £100 even if It nets me ten times my money.
Dippers are selling their second choice for £20m, they signed mamardashveli last year for £30m, we'll probably end up paying about £50m for Costa, theres not a chance Ederson is worth less than any of them and thats before factoring in the Saudi tax, everybody seems to get about 50% more than they're worth from Saudi unless its us.
I'm also concerned with Costa being good enough. admittedly i've not seen much of him of late and it's entirely possible he's improved substantially since then given his age but when i saw him when he was first making a name for himself i got the same impression of him as I did with onana at Inter. Don't think he's any better than Ortega with the ball either.