SAN FRANCISCO -- For millions of Americans who hung onto every last leap, bound and rescue of Miles Scott's heartwarming Make-A-Wish adventure, there's no putting a price tag on a nation's restored faith in humanity.

But when Batkid returned to his Siskiyou County home with a key to the city in tow, Gotham morphed back into San Francisco, and the city was left with a $105,000 tab for the stirring celebration.

The bulk of the bill, which city officials say was paid for using Moscone Center convention revenue, stemmed from the Civic Center celebration where Mayor Ed Lee, police Chief Greg Suhr and other city leaders presented the chocolate key to the 5-year-old leukemia survivor in front of as many as 20,000 revelers. Because the crowd exceeded Make-A-Wish's early estimate of 500 volunteer spectators nearly 20 times over, significant audiovisual upgrades were required to accommodate the turnout.

"We were told to expect over 20,000 people, and that requires a whole different setup than if a small crowd arrives to watch Miles shake the mayor's hand," said mayoral spokeswoman Christine Malvey. "People weren't going to see any of that in a crowd that large, so we brought in large video screens and AV stages so people could see Batkid."

"I think the public appreciated that, and we appreciated that Miles brought smiles and hope to children in our city and to kids living with cancer all over the world," Malvey added. "We're proud of what he's overcome, and we're proud of San Francisco."

The good will fostered by Miles' wish extended across all facets of the project, Malvey said, and an oft-used vendor for events like fireworks displays and parades near AT&T Park donated time and labor to offset the cost to the city. Department of Public Works employees were also asked to stagger shifts and redeploy resources for cleanup, but no extra costs incurred.

While a slew of police officers were called upon to secure Batkid's adventures, which began with the rescue of a damsel on the Hyde Street cable car tracks and ended with the ceremony in front of City Hall, San Francisco police spokesman Officer Gordon Shyy said no additional police units were deployed, and the department did not offer or pay out any overtime costs. According to Shyy, a group of on-duty motorcycle officers were the only law enforcement that actually followed the procession, and all other officers who provided security and crowd control would have been positioned in their various posts anyway.

"The event started in the Central District, where there were already officers working the area," Shyy said. "When it moved to the Southern District, that district's officers monitored the situation from there."

He added, "The motorcycle officers were already working, so they were just assigned to provide security detail. It's the same they would have done if the president was in town."

San Francisco Supervisor Eric Mar, who elicited an early outcry from Batkid supporters who felt he put a damper on the day's festivities when he tweeted "Wondering how many 1000s of SF kids living off SNAP/FoodStamps could have been fed from the $$," did not return calls for comment Wednesday. Mar reacted to the criticism in a statement Friday that he "simply wanted to urge that we, as a city, find similar amounts of love, compassion and empathy for children living every day in dire circumstances who, in the vast majority of cases, will not be supported or even recognized by our society."

Malvey offered that in light of the extraordinary turnout, the Make-A-Wish foundation will fundraise to offset the city's bill, an effort that will help minimize the costs but is not in any way expected.

"We'll be working with them in coming months to see what they can raise from donors, but we don't expect anything in return," Malvey said. "The city spends unexpected money all the time, be it rallies, protests or, in this case, a hopeful celebration -- it's a cost we're obligated to fulfill."

Contact Erin Ivie at eivie@bayareanewsgroup.com. Follow her at Twitter.com/erin_ivie.