The expansion is due out on March 25 of next year, but if you decide that you are planning on picking up the additional content when it is released, you may want to consider getting the Digital Deluxe or Collector's Editions of Reaper of Souls. (thatvideogameblog.com)
There were some Trinidad Scorpions in there, I think a pack of Carolina Reapers in there as well. (scottrobertsweb.com)
The Rise of the Necromancer downloadable pack doesn't have a solid release date or price yet, but since it's not a full - fledged expansion, it almost definitely won't cost as much as Reaper of Souls ($ 40 upon release). (tomsguide.com)