Ebay. Unlike the plushies from a while back, Zecora does specifically match the same style as the other miniature collection set ponies. We also have the spa ponies popping up on Taobao, so adding Ponyville's resident witch doctor isn't that much of a stretch.
I wonder who from the mane 6 will be bundled with her? We can probably assume Rarity or Fluttershy will be included with the spa pony, I can't really think of anyone other than Twilight Sparkle that frequently interacts with Zecora though, and she has already been used!
Regardless, these sets rock, so keep them coming Hasbro!
Thanks to Noah for the heads up!
(Discord/Trixie/Chrysalis set plz?)