The money is to go to Princess Beatrice's charity, Little Bee Initiative

It threatened to upstage Kate and William on their wedding day, being compared to an upright toilet seat and a set of fallopian tubes. But last night, barely three weeks after being dubbed "fashion roadkill", the hat worn by Princess Beatrice was on course to sell for more than £80,000.

The Philip Treacy-designed headwear has attracted more than 100 bidders since it was put up for auction online. They include Duncan Bannatyne of Dragon's Den, as well as anonymous US bidders, whose fixation with the monarchy led to a flurry of late bids on Friday. And from Australia, the children's TV performers The Wiggles offered £17,500 for a chance to own one of the most polarising pieces of headwear ever seen. "We wear some pretty crazy costumes on stage but this hat beats them all," said Wiggles frontman Anthony Field.

Bidding is set to close today, after which the hat will be carefully dispatched to one "lucky" winner. However lucrative the auction proves, Clarence House insists the profits will bypass its own coffers, heading instead to the Little Bee Initiative, a charity founded by Princess Beatrice to raise money for Children in Crisis and Unicef.

The headwear, originally the subject of hostility and ridicule, has become a cultural sensation on the internet, appearing on the heads of numerous celebrities, including Donald Trump, Vladimir Putin and Lady Gaga. Meanwhile, the "Princess Beatrice's ridiculous royal wedding hat" Facebook page has more than 142,000 endorsements.

Experts believe the hat's popularity in cyberspace could help its value to rise. "It is a piece of headwear forever immortalised online," said Harriet Quick, features editor of Vogue magazine. "As a piece of fashion, it is surreal, tangentially bizarre, different and eccentric. But it could also become extremely profitable."

For all the criticism levied at his creation, Treacy, whose hats also adorned the heads of the Duchess of Cornwall, Victoria Beckham, Tara Palmer-Tomkinson and 31 other wedding guests, remained defiant. "The hat is a symbol of positivity," he said. "I hope people all over the world will be generous and the hat will benefit many."