I find the old "the club want to sell" argument very tired to be honest.
The club technically want to sell any player that is contracted if the bid is good enough. That goes for 99% of teams in world football. If someone offered £500m for Messi now, Barcelona would look at it seriously and a good part of them would want to sell the player as a result.
So of course Everton would want to sell Stones for say £50m. We'd be stupid not to - as that is above and beyond his market price now and probably as much as he'll ever be worth.
The issue isn't that for me - the issue is whether we need to sell.
I'm not one of those who thinks the money we get from transfers disappears - it generally doesn't (except for Arteta, which was robbed from the squad. Fellaini/Rooney was reinvested etc.). My concern is that despite massive money flowing into the game in England, we are average on wage spend and massively below average on transfer spend. With that being the case, we should at the very least not need to sell players if we don't want to.
If we do need to sell to buy, then the only explanation I have is that some pretty serious level fraud is going on behind the scenes. If we end up selling Stones for anywhere near £30m, that would be frightening to me, as it'd indicate we couldn't afford to stand our ground and say no.