Boeing Co. could be getting some prime real estate at Charleston International Airport for a bargain.

The Charleston County Aviation Authority voted 8-3 Thursday to sell the aerospace company 320 acres across from Boeing’s 787 campus for $12.5 million.

Both sides have 30 days to back out of the $39,000-an-acre deal.

Boeing has not said what it intends to do with the International Boulevard property, but it has stressed that it doesn’t bank land or intend to sell it for another purpose.

The two sides arrived at the price based on an agreement requiring them to split the difference if their own appraisals were within 10 percent.

The first set of appraisals came in at $27.6 million from the authority and $19.9 million from Boeing, according to appraisal documents released from the Aviation Authority on Friday.

Board members rejected those estimates as being too far apart and asked for a second round from different firms.

Boeing’s new appraisal came in at $13 million. The airport’s was $12 million.

“We decided to roll the dice,” said Charleston County Councilman Elliott Summey, who was sitting in for his father, North Charleston Mayor Keith Summey. “It didn’t come up with what we wanted.”

Summey said the airport’s first appraisal valued the land as if it was ready for development. So the costs of filling the numerous wetlands and removing a radar site were not considered.

“This property is not ideal to develop real estate in,” Summey said.

Some board members tried to postpone the vote to give a committee time to review the appraisals. Others said the appraisals, which came in Wednesday, were within the contractual parameters and there was no need for a delay.

Boeing attorney Mark Fava said he preferred that the board make a decision Thursday so that the company could start seeking clearance from the Federal Aviation Administration and the Army Corps of Engineers.

Board member Tommy Hartnett, who is an appraiser, said he was baffled by the rush to vote.

“We have one bite of the apple,” Hartnett said. “I don’t know if it’s right to let that land go at that price. It would be foolish to do that. That land has been sitting there for eons. I don’t think it will change anything to wait.”

Charleston Mayor Joe Riley, who also sits on the board, countered that the appraisals were close enough to cement the deal.

“Splitting the difference is the normal business practice,” Riley said. “This is a land sale and, more importantly, an economic development matter. The economic opportunity to the community and for the future are huge.”

Boeing officials said they were pleased with the deal.

“We believe that the average appraised price as agreed to by the parties provides the accurate, fair-market-value return to the Charleston County Aviation Authority,” Boeing spokesman Tim Deaton said. “The price was negotiated in good faith pursuant to a contract the parties agreed to last December. While Boeing does not have specific plans for the property, the acquisition will provide strategic land for possible future use.”

In earlier reports, Scott Hamilton, of Issaquah, Wash.-based aviation consulting firm Leeham Co., and other experts think the extended 787-10 will be assembled in North Charleston. Hamilton also has floated the possibility of the 777X or the eventual successor to the 737 MAX being made in South Carolina.

Aerospace analyst Richard Aboulafia, on the other hand, downplayed the idea of a major shift to South Carolina. He said it’s more about Boeing wanting options.

“It’s unlikely that this facility will be used to stand up a corps of engineers like they have back in Washington,” said Aboulafia, of The Teal Group. “I think it’s more of a broader message.”

Note: Because of incorrect information provided to The Post and Courier, the first appraisal conducted for the Aviation Authority came in at $27.6 million and Boeing’s first appraisal came in at $19.9. The previous reported figures were incorrect.

Brendan Kearney of The Post and Courier contributed to this report.