Last night there were 38 bidders competing on eBay for the headpiece, which sparked controversy among fashionistas during Kate and William's big day.
The leading bid on the auction website - which ends just after 5pm today - stood at 75,110.
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Hide AdRoyal Wedding watchers compared the flamboyant Philip Treacy creation to a Turkey Twizzler, a toilet seat and a pretzel, and Facebook pages sprung up in its honour, attracting thousands of followers.
Undeterred, the 22-year-old princess decided to sell off the item for charity, with Unicef and Children in Crisis to benefit from the funds raised.
She wrote on the auction page: "I hope whoever wins the auction has as much fun with the hat as I have."