No one knows what the fee is. There are no quotations by club officials in the public domain and the media exagerate everything to do with Manchester City spending. The only thing that looks likely is that City paid a release-clause because VIlla were powerless to turn down the bid. So what was that set at? We don't know. The most quoted figures are either £75m, or £75m rising to £100m but there is no point an agent agreeing a release clause unless it can be exercised by a number of clubs. If you're targeting MCFC and you know their record fee is £65m, you don't see that release clause at £100m so I suspect the fee could be lower than what's been rumoured.
The most quoted figure is 100m. By everyone. 75m came from one tenuous source only. I can believe it myself, but not rushing to based on that one claim, nor do I feel any need to.
You are right, nobody knows, not sure if we ever will. Not really any different if it was 1m and 99m in add-ons. The headlines have already been written as 100m and stuck, no pulling that back now even if a true fee gets reported at some point.
The excitement in his signing is enough for me.