A while back, we posted this spa pony mini someone leaked over on Taobao. It looks like Big Bad Toy Store already has it listed, though no image is included to show off the other two characters that she will come with.
Before you jump up and order it though, do note that they have listed unreleased toys before, then sent the wrong ones when people actually order them.
They also have 8 packs of the Cloudsdale, Wedding, and Spa Pony sets. These are most likely just the boxes they come in, as Target's stock straight from the factory came in sets of 8.
Thanks to Whatshisgame for the heads up!