Obviously,
Simplicissimus buys in bulk from Bookeen (and from iRex - check their 630 € iLiad !) and gets a substantial rebate.
BTW, there's another italian hi-tech retailer,
Bow.it, offering the Cybook for 339 €. But AFAIK, they only ship to adresses in Italy.
Not so with Simplicissimus: I tried, and succeeded, to register with a address in France. Shipping to other countries is available, too. And their S&H rates are very reasonnable too.
Edit: Oops, BKeeper beat me to it! ;-)