It's called a joint order. That is you order two or more items in one shipment from the same supplier.
There are many ways to proportion the S/H costs to many items.
I used the assumption at all four items (V2b stickers, V3b stickers, V7 stickers and the V4b cube) had equal S/H cost so you could
divide the S/H part into four equal parts, so it made the stickers much more costly than getting them from cubesmith and the V4b
cube is much cheaper in the process. This is called charging by volume, not weight. Many couriers actually charge S/H by volume rather than weight.
You can put a feather into a 1m x 1m x 1m box and send it. Charging by volume assumes the feather uses up all the space in the box,
even though it does not. Charging by weight only considers the weight of the box and the feather. As more and more stuff comes to us
by air and not by sea, charging by volume in airplanes with limited storage in volume capacity is more natural.
Anyway you do the calculations, the V4b is a very, very expensive 4x4 cube.
And unless you buy every puzzle product from a bricks and mortar (ie phyiscally present and standing) shop, this stuff should be considered.