Why the heck is Balthazars Bag of Bottled Faeries such a high value NC item?

I just looked it up on dress to impress and it's not even that great. NY in Faerieland I can understand because it's a very pretty, girly BG and girls notoriously love customisation but the bottled faeries I just don't get

140 caps? That's like....crazy amounts of money hah