Probably more like Neymar money...150-200m.
I think he would pay it if it were possible. That's sort of where we are now, if you want players to improve the starting XI you have to get the very best of the best. Mahrez will be 60m or so and he'll be a good part of the machine, but he won't take the side to the next level.
And he's made it clear we don't need a lot of players, so we can afford to go big on the ones you do go for.
Personally I think Hazard might bring a lot more complications, but if Pep thinks he can juggle the players, he's earned the right to go for it.