actually there is somebody who figured out how much it costs: look at attachment
till now, for me the best sale to pay for is (if i would pay): an event pass (gives a lot of troops, vip points, crowns,artifact, speed ups..), or the 5 dollar packages that gives 20 vip points
in most sales the value is 1 dollar: 2vip points -> 10 dollar = 20 vip points