"It's a very unique situation. I don't think most team sales or valuation analyses you do are like this," Morgan Stanley managing director Don Cornwell said Thursday at the Bloomberg Sports Business Summit in New York.
Cornwell said the situation was unusual because it was a team in the second-largest American city, and there is the potential for a lucrative media sale.
"I don't see people coming to us and saying, 'Hey, they're worth $2 billion, I'm worth $1.8 billion,'" Cornwell added. "'I'm not paying a Ballmer price.' That's sort of the new phrase we're hearing a lot."
The deal was rational to others at the conference despite the high price.
"It's not crazy to think he might be right," Lyle Ayes, co-head of Evercore's sports group, said of Ballmer's bet on selling media rights.
Ayes said sports teams continue to be an attractive investment for the ultra-wealthy.
"They're certainly uncorrelated with the general economy. If you look at sports teams, the music likely will stop one day, but I certainly won't call the top," he said.
Ayes noted that low interest rates help.
"At the end of the day it's a trophy asset purchase and so they're willing to dip a little deeper to make the numbers work. But in a low interest rate economy, if you can earn some yield ... it's getting harder and harder to lose money in some of these sports with the media right deals," Ayes said.
"I don't know that the economy will derail it. If it's competing with a 5 percent yield then maybe the prices come down a bit. But as long as it yields and the asset values continue to either go up or stabilize, I think you'll have buyers that are always there."
"'Now I know I don't have to continue to write checks. Now I know there will be some sort of cash coming back in,'" he said of how prospective owners think, noting media rights deals and relatively predictable costs. "That helps a lot."
-By CNBC's Lawrence Delevingne