Ayano found this one a couple days ago. SincereMasterpieces on Etsy makes made-to-order Krystal plushes. These are 12 inches tall and have wire supports to keep her standing. The head can turn as well.

The listing is a little confusing, but it looks like she's willing to make Krystal plushes like this one even though the listing says "Sold Out". If you're interested, contact her about it on the Etsy Krystal Plush Listing.