Battle.net is the official website of Blizzard where we can acquire all the great successes of this company at the official price. To buy, we must create an account and then download the client where all the games that we are buying will appear. The shipping time after the purchase is instantaneous, and the methods of payment are: PayPal and credit cards.
Official Blizzard Store with Blizzard Games and Deals. Nothing more. It is a more specific store than official stores like steam or green man gaming.
Official site, you won't have problems buying the product in battlenet. You can find the game for 20€ some times when blizzard does ofers. Its a nice game.