WASHINGTON — After he is out of the White House, President Obama has said that he wants to become a venture capitalist, own part of an N.B.A. franchise and avoid taking off his shoes during security screenings at commercial airports.

All of those goals, serious or not, might soon be achievable if Mr. Obama and his wife, Michelle, sign post-presidency book contracts for what literary agents and major publishers say could amount to $20 million to $45 million — more than enough to pay the estimated $22,000 monthly rent for the nine-bedroom home they will occupy in the Kalorama neighborhood of Washington and foot the bill for flights on private jets. (Mr. Obama has said he would like to avoid commercial flights once he surrenders Air Force One.)

“His is going to be easily the most valuable presidential memoir ever,” said Raphael Sagalyn of the ICM/Sagalyn Literary Agency, who predicted that Mr. Obama could earn as much as $30 million with a two- or three-book contract. “And I think Michelle Obama has the opportunity to sell the most valuable first lady memoir in history.”

Other agents suggested similar numbers, but publishers — who are the ones who actually sign authors’ checks — balked at such lofty evaluations, with several saying Mr. Obama is unlikely to earn more than $12 million and Mrs. Obama $10 million.