Hmmm......interesting. I think that's because they're based in the US. It's same as Amazon.com (US site). The prices of some products are not displayed straightaway & can be seen only after adding the product in the cart,
like this.
This is what Amazon says about the issue:
Retailers like Amazon have the legal right to set their own prices independently, but some manufacturers place restrictions on how those prices may be communicated. Because our price on this item is lower than the manufacturer's "minimum advertised price," the manufacturer does not allow us to show you our price until you take further action, such as placing the item in your shopping cart, or in some cases, proceeding to the final checkout stage. The steps required depend on the details of the manufacturer's minimum advertised price policy. Taking these steps allows Amazon to show you our price consistent with our goal of always offering you the lowest possible prices on the widest selection of products.
This won't require you to purchase the product. You can easily remove it from your cart if you decide not to buy it.
We realize that this is an inconvenience and are regularly working to educate manufacturers on how their policies impact our customers.