Online bidding for the pistol used to shoot and kill an unarmed teenager appears to have been inflated to $65 million by fake buyers such as "Racist McShootFace".
George Zimmerman drew wide criticism on Thursday after offering to sell the Kel-Tec PF9 9mm handgun, which the former neighbourhood watch volunteer used to shoot unarmed black teenager Trayvon Martin in 2012.
Mr Zimmerman described the weapon in the auction listing as "an American Firearm Icon".
He said the weapon was used to defend his life and "end the brutal attack" from Mr Martin.
Mr Martin's family has said the 17-year-old was simply walking home after buying a drink and candy from a local store when he had the fatal encounter with Mr Zimmerman.
Martin's killing near Orlando, Florida, sparked nationwide civil rights protests and debate over "stand your ground" laws, which allow people to use deadly force without a duty to retreat if they are in fear of being harmed.
Mr Zimmerman was acquitted of second-degree murder and manslaughter charges in the case.
By lunchtime on Friday, bidders in the auction on the United Gun Group's website included "shaniqua bonifa" and "Tamir Rice," the same name as the 12-year-old black boy shot dead by a white police officer in Cleveland in 2014.
The auction is scheduled to end on Wednesday. USA Today reported that the bid by "Racist McShootFace" was later deleted.
The auction began on Thursday after the first site where Zimmerman attempted to sell the gun rejected the listing. That site, GunBroker.com, said in a statement that it wanted no part in the auction or the attendant publicity.
'Letter of the law'
The new listing for the gun appeared on UnitedGunGroup.com with a starting price of $5000. By midday on Friday it had received more than 1000 bids.
United Gun Group said in a statement that as long as Mr Zimmerman was obeying "the letter of the law," the sale of his personal firearm would be allowed on the site.
"While not always popular, this is where we stand. There are principles this nation was founded on, and our goal is to do our part to defend liberty," United Gun Group said.
"We know that many lives have been forever impacted by the incident February 26, 2012, and we're truly sorry to the Martin family for their loss. We will have no further comment on the matter."
The website calls itself a "free social network and marketplace that embraces the 2nd amendment and lawful discussion".
The Second Amendment to the US Constitution is "A well regulated militia, being necessary to the security of a free state, the right of the people to keep and bear Arms, shall not be infringed." It is contained in the United States Bill of Rights.
In the auction listing, Mr Zimmerman said he would use money from the sale to counter violence against law enforcement officers by Black Lives Matter, a movement that grew out of Martin's shooting.
Proceeds would also go towards fighting Democratic presidential hopeful Hillary Clinton's "anti-firearm rhetoric," Mr Zimmerman said.
According to the listing, the pistol was marked with the number from the Martin case in silver ink and the listing included multiple photographs of the weapon being displayed in court during the trial.
The listing closed with a Latin phrase, "Si Vis Pacem Para Bellum," meaning "if you wish peace, prepare for war."
A lawyer for Mr Martin's family called the sale offensive but said it would not distract the family from their work advocating against gun violence.
Mr Zimmerman has previously sold on eBay a painting depicting the American flag, and a painting he did of a Confederate flag to raise money for a Florida gunshop owner who declared his store a Muslim-free zone.