BlizzCon is only a couple of months away and the Virtual Ticket is now available for purchase. The price of the virtual pass is $39.99 and grants access to a livestream of the developer panels, exclusive interviews, live contests hosted by Chris Hardwick, the closing ceremony, and various in-game items. Additionally, you'll be able to participate in the limited-time BlizzCon merchandise sale on the Blizzard store, most of which is generally only available at the convention itself.
You can acquire your virtual pass via the Blizzard Store. If you have any questions, refer to the virtual pass FAQ on Battle.net.