The cost of gas to transport it and propane to fly it has more than tripled since Gary Waldman of Iowa first launched the balloon in honor of his daughter Serena in 1991.

"It's been just a wonderful, wonderful experience for us," Waldman said. "I hate to see it die for lack of funds, but $4 gas and $3 propane cuts into your bottom line."

Gas was $1.25 a gallon when he started, he said; propane, which powers the balloon, was 50 cents.

Waldman's inspiration for the balloon is his daughter, Serena, who was born in 1983. During birth, she bled to death and was declared dead for 21 minutes before a nurse, preparing her for an autopsy, saw her take a breath.

Doctors gave the family little hope when the Waldmans took her home. She has severe brain damage and cerebral palsy.

Waldman became a stay-at-home dad to care for Serena.

He had been a longtime hot air balloon enthusiast when a friend offered a ride two years after Serena was born. He took her along.

They heaved Serena's wheelchair on board, wrapped her with a moving pad and tied her to a fuel tank to make sure she didn't move as they rose into the air. The balloon was tethered to the ground.

That's when he saw Serena's first smile. Her first laugh. She hadn't expressed emotion before that day.

"She was squealing and having the best time," he said. "I looked around and everybody was in tears."

Waldman wanted to bring that experience to other parents with children with disabilities.

Six years later, he had gathered enough goodwill and donations to launch Serena's Song, which is specially designed with a door for wheelchairs to roll in. To accommodate them, it's bigger than most balloons.

More than 20,000 families have gone up. Rides are free.

Corporate sponsors and even a race horse have helped keep the balloon afloat. But Waldman said he has no prospects now for major financing. It takes about $100,000 a year to take the balloon to 10 events.

It's the fourth year the balloon has stopped in Raleigh. Raleigh's Capital Area Transit and the city's Parks and Recreation Department sponsored the visit, which always delights the children who ride.

"Once you see one of them smile like crazy, you're pretty much hooked," said Scott McClellan, general manager of Capital Area Transit.

Waldman said he hopes a donor will come through.

"It's never been easy," he said. "This has been a fundraising struggle from day one just to keep it flying. The good Lord has always provided for us with a way. God knows there's money out there. But finding it is the hard part."