JOHN YANG: Finally tonight, if you're in the market for some rare presidential memorabilia and you've got deep pockets, have we got an auction for you.

JOHN YANG (voice-over): This is one of the rarest American flags in existence.

ARLAN ETTINGER, President, Guernsey's: April 14, 1865.

JOHN YANG (voice-over): And it's about to go on the auction block.

ARLAN ETTINGER: Certainly amongst the marquee items is this really quite significant flag that draped the coffin of President Lincoln following his tragic assassination.

As the coffin was loaded onto a train in Washington and then embarked on a historic run from Washington to Philadelphia to New York City, on to other stops as it made its way to Springfield, Illinois, where the president was buried.

JOHN YANG (voice-over): April 14, 1865, the Civil War had ended.

Just days before, a war weary Abraham Lincoln went to Ford's Theater in Washington to see a popular comedy of the day, our American Cousin.

As the audience reacted to one of the play's biggest laugh lines, actor John Wilkes Booth entered the presidential box and shot Lincoln in the head.

Items related to Lincoln's assassination are so rare they tend to sell for high prices.

A wanted poster for Booth sold for more than $160,000.

A pair of tickets for that performance over $260,000.

Even scraps of bloody fabric from the dress worn by an actress in the cast that night have commanded top dol.

ARLAN ETTINGER: When you have something that's completely unique in all the world, how do you guess what it may be worth?

JOHN YANG (voice-over): Top estimated price, $1.2 million.

The Guernsey's auction in New York later this month includes other presidential artifacts.

Some never before seen in public.

There's a lock of George Washington's hair.

ARLAN ETTINGER: It was first given to a family friend of the Washingtons and their descendants kept a record of it very religiously through the generations.

JOHN YANG (voice-over): And portraits of Franklin and Eleanor Roosevelt and Jackie Kennedy on her wedding day.