Waves 20 & 21 have been in my Walmart for ages now, and I've also seen 21 at Dollar General before. I've never seen Wave 19 in person, as well as Wave 23, until the pony fair. I know 20 and 21 were available, but I also want to know where/if 19 & 23 were released around the US. I also have never seen Wave 18 in my area, but I have seen them at Walgreens in Florida (when I went to pony fair, I did a little shopping around as well.)