I know someone else was asking why there wasn't a Sagittarius too. Perhaps the astrovibes have been discontinued and those were the most popular, so sold out fast.
They actually had every single sign in stock at one time EXCEPT for the Sagittarius. For some reason, the Sagittarius was the only one that was never stocked. I kept waiting for it, but there was never even a product page for it (at least that I could find)---and I even started looking for it the day the Astrovibes were introduced. I also regularly followed up in searching for it.