Luna and Celestia are extremely hard to find. They were barely on the shelves when they were released in December, and Hot Topic had them up on their site sporadically, but it's been a good few months since they were last up.
I was thinking they may have been waiting to rerelease them due to the broken tail issue that a lot of people had, but we're now on a second wave of ponies since Luna and Celestia were released with no indication that we'll actually see them again.
Their release here was so terrible, though. Constant push backs in the actual release date, broken parts for both their regular and glitter variants (more so with Luna), some stores never getting them at all...
So yeah, no idea when/if we'll see them again here in the US or anywhere else. I feel bad for anyone who wasn't able to get them, because they're absolutely gorgeous figures. I hope there's a rerelease for those who missed out! *fingers crossed*