9:26 AM PT -- A rep for Costume Agent, which originally created and distributed the controversial Caitlyn costume, tells TMZ they're not yanking it from their own site, and certainly not discontinuing it ... backlash be damned.
We're told the 'stume is one of their best sellers -- it's the #6 overall bestseller. Although they have received multiple threats over it this past week, they're standing by their product. The rep says, "It's a costume. It's funny."A Caitlyn Jenner costume -- which harkens back to her Olympic glory days as Bruce Jenner -- is getting destroyed by critics who say it's insensitive to transgender people .