A Gulfstream G4 from 2002 might cost $3 million — far better than $60 million plus for the current G650. But that old Gulfstream still costs $1 million or more a year to operate, he said.

"Even if you're very wealthy, you could still be shocked by a monthly bill," he said. "We want to include the owner in how we make money. It's for guys who are used to having information at their fingertips."

Still, some buyers don't want to share.

A lawyer who advises on jet purchases said the plane was just another asset for his billionaire clients. Many of them are happy for the plane to sit idle when they're not using it, even if it entails paying for a crew to be at the ready.

Management companies like Executive Jet Management, a part of Berkshire Hathaway's NetJets, and Solairus Aviation focus primarily on managing jets for the owners, which includes negotiating down fixed costs like fuel and pilot training but also ensuring compliance with flight and safety regulations.