We can now clearly see that these sets are based on the Season 1-episode, with both spa scenes as well as clothing shoots with Photo Finish. The dresses from Sweetie Belle and Scootaloo in this case are from the "For Whom the Sweetie Belle Toils" episode, which aired later in Season 4.
With the huge amount of release in the past few weeks and this announcement in the UK magazine are strong indications that these sets will be sold very soon. Below we've included the original Amazon listings for all sets, which will hopefully be updated with high quality stock images soon!
Thanks to Robbie for the images!