A small New York novelty store has put a US$15 million ($21.5 million) price tag on a singing mechanical bird that is at the centre of a celebrity storm.

Grammy-winner Kelly Clarkson claimed she was treated like Julia Roberts in Pretty Woman when she sought to purchase the $US15,000 ($21,500) item in Art of Play and “was looked at as if I couldn’t afford it”.

“Wow, dude. You’re an idiot and just lost a huge sale,” she ranted on X.

“But y’all should go check out Art of Play in Brooklyn if you enjoy being treated like Julia Roberts’ character in Pretty Woman. For sure, check it out,” she said, referring to the scene in which a prostitute is snubbed in an upmarket boutique.

The store responded on Instagram by stating that the bird, Molly, was the store’s mascot and not for sale.

The store said the sales attendant had suggested the Since U Been Gone artist could buy an identical bird for $US15,000.

The singer hit back: “So the whole conversation we had when I asked you if it was for sale whilst pointing to the price tag hanging on the wall with the title Singing Bird didn’t happen as you elevator-eyed me saying in a condescending tone ‘yes, it’s for sale but it costs 15,000 dollars so if you’d like me to find something comparable for you I can’.

“That all never happened and now it’s not for sale. Okay, cool. So you’re not only rude, you’re also a liar. Got it.”

Art of Play said Clarkson’s public criticism to her millions of followers had unleashed a wave of social media backlash.

The Art and Play store on Atlantic Avenue in Brooklyn, New York. Photo: AAP

“Imagine our surprise when our small local business was suddenly attacked by eight million people who have never visited our store,” Art of Play said.

“It’s been a surreal experience to be the focus of such widespread outrage after just one mention by a celebrity.”

The row has sparked massive media and public attention.

The locally owned business was reportedly crammed with television cameras and journalists following the story this week.

After initially making it clear that Molly was not for sale, a co-owner told media that it now had a $US15 million price tag.

Adam Rubin told NBC News that if the bird sold he would give each store employee a $US15,000 bonus and send $US1 million to the bird’s artist.

Clarkson insisted she was a supporter of small business.

“I obviously support small businesses because I was literally at a small business trying to purchase things.

“I love small businesses and know they are important and I always support them, but you don’t get a free pass to treat people less than in your store just because you are a small business.

“It’s not that hard to be kind. I never blast people but you my friend were an exception.

“Your store is really cool.  Unfortunately, you aren’t.”