Diablo III fan because Blizzard has put a street date on Reaper of Souls: March 25th, 2014. This release date is for the PC and Mac only, with the PlayStation 4 release date to be announced later.
Even though you won't be able to play the expansion for three months, you can pay for it today. That's so considerate of the studio, isn't it? Those who pre-purchase Reaper of Souls have the choice of three editions. The standard edition is $39.99 and the digital deluxe version (with extra goodies like a spectral hound minion) is $59.99. Alternatively, you can try to snag one of the collector's editions (with extra extra goodies) for $79.99 at select retail stores.
The expansion includes a new act, the Crusader character, the Loot 2.0 system, more class skills, new modes, and more.