A man accused of swiping $1 million in rare books from the collection of a late Vanderbilt heir sold 250 titles for a total of $500,000, the dealer who bought them said yesterday.

The dealer, who asked not to be identified, said the Manhattan district attorney is trying to determine if some of his purchases — including Hemingway’s “The Old Man and the Sea” and “In Our Time” — came from the plundered collection of Carter Burden.

The alleged thief, home-electronics installer Timothy Smith, is free on $250,000 bail.

“The book business is a very tough business,” the dealer said. “I really stepped up to the plate and paid big, big money . . .and it’s probably all lost.”