I would either recommend PHPurchase or Shopp for WordPress. Each have their own pro’s and cons in relation to set-up and features. Both of the below plugins are not free, but a lot of free e-commerce solutions like WP E-Commerce sometimes just aren’t enough to build a great online store.
PHPurchase
Allows you customise every aspect of it, only downside is that to truly customise it you need to have a bit of PHP coding knowledge, otherwise you’ll find yourself swimming in a shark infested ocean so-to-speak. It allows for physical and digital sales, advanced product variations as well as a whole heap of other stuff.
Shopp
Shopp is one of my favourite e-commerce plugins. It doesn’t require PHP coding knowledge like PHPurchase and it has just as many features, if not more. It can support two-tiered product variations and has quite a lot of payment gateways. It also offers shipping variations and various shipping calculators, etc.
In my opinion if you choose Shopp you won’t be disappointed. It can do everything that those shops you linked too offer.