In June 2000, Bunker, now 40, and his wife, Adrienne Redd, bought this dream house for $2 million.
A massive federal tax break was included in the transaction.
As part of the sale, Bunker and Redd signed an agreement promising never to subdivide their surrounding property, a pastoral oasis of rolling grass and towering oak trees.
In exchange for this preservation agreement, they qualified for a $1 million tax deduction. Bunker said the onetime deduction saved his family $400,000 in taxes.
Their mansion is three football fields from Gravers Lane, and cannot be seen from the public road.
Thus, for forgoing $400,000 in taxes, the public protected 18 acres of open space down a private road from which it is barred by a cattle-crossing stop sign. All perfectly legal.
In all, seven buyers got a piece of the estate when the University of Pennsylvania sold the 32-acre property.
In addition to the $2 million from Bunker and Redd, the six other buyers paid another $2 million for the remaining 14 acres. Those six shared the right to a $900,000 tax deduction for banning further subdivision on their land.
In summary, the estate sold for $4 million. The seven buyers, by granting the preservation easement, qualified for a total tax deduction of $1.9 million.
The amount saved in taxes depended on each of the buyers' tax brackets.
Of the buyers, four bought houses and land on the estate and three bought land to add to their existing estates on the edge of the Wharton Sinkler property.
Among those adding to their parcels were David P. Montgomery, president of the Phillies, who added about an acre to his 1 1/2-acre property; and pharmaceuticals millionaire Robert L. McNeil Jr., who added 3 1/2 acres to his 8-acre homestead.
Peter Lapham, executive director of the Chestnut Hill Historical Society, and his wife, Emilie, bought one of the houses within the estate. Their new home, just off Gravers Lane, is a picturesque craftsman's cottage, built in 16th-century England and shipped to America brick by brick 80 years ago.
Lapham said that even without the tax incentive, he and his wife would have bought the cottage.
The deduction, he said, "was not a factor. It was certainly a benefit."
An appraisal determined that the seven buyers of the Wharton Sinkler estate had given up the $1.9 million in potential development value in signing an easement protecting the open space.
Therefore, they were entitled to share a tax deduction of that amount.
The laws governing tax deductions and open-space easements don't require that the general public be able to use the land - or even be able to see the buildings on it. It is enough that the open space is protected.
And parts of the grounds of the 32-acre estate can be seen from Gravers Lane, though not the main house.
The preservation easement for the entire estate was accepted by the North American Land Trust. The Land Trust, founded in 1992, holds easements on 10,000 acres in five states, according to Andrew L. Johnson, who helped found the trust.
The trust is based in Chadds Ford and shares a small office building with Edgar Scott 3d, the broker whom the University of Pennsylvania hired to handle the sale.
Johnson, who holds a master's degree in environmental studies, said that construction of a housing development there would have produced water and fertilizer runoff harmful to the Wissahickon Watershed.
Government regulations could not be trusted to control such environmental threats, Johnson said.
He said 63 houses could have been built on the Wharton Sinkler estate if the easement had not been given by the new owners.
"How many children do you have to put in public school when you have 63 houses?" he asked. "It costs everyone else in the neighborhood money."
Bunker may not stay in his mansion for long. The place is for sale for about $2.2 million. Bunker said he spent $500,000 for renovations.
His pledge to forbid subdivision of the property has narrowed his financial options, he said.
"We were the ones that gave up value," Bunker said. "I could use the money now, in a real sense."
Still, Bunker expects his fortunes to rebound.
"Once we sell the house," he said, "I'll be a millionaire again."