He isn't saving 100€ at all if Amazon's prices are higher than the competition, which is almost always true for every product I ever checked during the last five years, at least.
Prices vary wildly across Europe. Countries like Serbia have absolutely insane prices for basic products that are two thirds or half the cost across the border, sold by the same companies.
As much as Europe wants to be a single market sometimes, every country has different cultures and different economic situations. Where I live Amazon is never the cheapest option (and almost never the fastest to deliver), but 20km to the east of me it's a valid competitor to many online storefronts.
