"Jim Justice has been absolutely wonderful to me," Keller said.
Keller said the purchase price was "less than $1 million, but a lot more than the price that was bid at auction."
The spacious Greenbrier has three 18-hole courses open for public play and has hosted the PGA Tour's Greenbrier Classic since 2010.
Conventional golf clubs aren't used at Oakhurst. Players - often dressed as if they had just come out of a time tunnel - rent hickory-shafted clubs and hit gutta-percha balls off tees fashioned from sand and water the way it was done more than 130 years ago.
The Greenbrier dates to 1778 and is a former gathering place for presidents and royalty. It has a 721-room hotel, casino, spa, dozens of amenities and a once-secret underground bunker built for Congress in case of nuclear attack during the Cold War. Justice bought the resort out of bankruptcy in 2009.
Though he has owned Oakhurst since 1959, it wasn't until 1994 that Keller reopened the course after it had been dormant for more than 80 years. The National Hickory Championship has been played at Oakhurst since 1998.
Oakhurst was first owned by Russell Montague, who became enamored with golf while studying in Great Britain.
Montague and a small group of colleagues held the first competition at Oakhurst in 1888 in the Scottish match play tradition, predating by a few years the St. Andrews Golf Club of Yonkers, N.Y.