eBay International Shipping : Random price increase.

Hello, I live in Europe and I usually order items from the USA. Recently I noticed something strange with the eBay International Shipping .
Let's take the example of a store : you will have a t-shirt with a shipping rate of 25 dollars and another at 50, another at 60.
All coming from the same shipping address and for the same destination.
Who is going to buy a shirt with a shipping cost of 70 dollars.
I would like to clarify that I am not talking about VAT which is automatically added to the price. Anyone know what's going on?

Thx