The figure was based on comparisons with the value of other expensive in the Washington DC area.
"When you add the historic value to it, the sky's the limit," Koitz told Movoto.
"We could realistically be talking the world's first billion dollar purchase for a single-family house."
By comparison, the British PM's house of residence, 10 Downing St, was valued at $7.3 million in 2010, while the Queen's Buckingham Palace has been estimated to be worth about US$1.6 billion.
The White House's 55,000 square feet contains 132 rooms, 35 baths, 28 fireplaces, 413 doors, 147 windows, eight staircases, a tennis court, bowling alley, movie theatre, basketball court, swimming pool and jogging track.
- Herald Online