NEW YORK (AP) _ They're selling Camelot piece by piece, and the prices are sky-high: nearly $50,000 for a tape measure, half a million for a humidor.

Sotheby's on Tuesday began a four-day auction of hundreds of objects _ including furniture, china, books and artwork _ from the estate of Jacqueline Kennedy Onassis.

In front of a crowd that gasped as the prices soared, most items sold for well over their presale estimates. A walnut humidor, a gift from Milton Berle to John F. Kennedy, was expected to sell for $2,000 to $2,500. It sold for $574,500.

An oak rocking chair JFK used in the White House went for $442,500. John F. Kennedy Jr.'s high chair and Caroline Kennedy's rocking horse each fetched $85,000.

``The sale started and it just took off by itself,'' said auctioneer Diana Brooks, Sotheby's president and chief executive officer.

The total for the night was $4.5 million; Sotheby's conservative estimate had been $516,000 to $718,000. The prices include Sotheby's commission, which is 15 percent of the first $50,000 and 10 percent of anything above that amount.

Prices quickly escalated for even the simplest items, like a silver tape measure from Tiffany's ($48,875), as bidders competed to own a piece of history.

``This is a big event,'' comedian Joan Rivers said. ``This and Halley's comet.''

The long-awaited sale of the belongings of the former first lady, who died of cancer in 1994, has generated an unprecedented level of hype.

In addition to the 1,500 people in the Manhattan auction house, about 300 potential buyers were hooked up by phone from the Chicago and Los Angeles offices of Sotheby's, which received 70,000 written or faxed bids.

``People will pay thousands of dollars for an ashtray not because of its intrinsic worth but because it belonged to Jackie,'' said Bruce Wolmer, editor in chief of Art & Auction magazine.

He said it was ``a safe bet'' that the Onassis sale would surpass Sotheby's 1987 Duchess of Windsor jewelry sale, which brought in $50 million.

The auction continues through Friday, with Mrs. Onassis' jewelry on sale today _ including a 40-carat diamond she received as an engagement gift from Aristotle Onassis.

Items later in the week include the wedding gown from her marriage to Kennedy, Mrs. Onassis' 1992 BMW, and even the doors from her White House dressing room.

The more than 5,000 items are being sold by her children, Caroline and John F. Kennedy Jr. Proceeds of the auction will go to Mrs. Onassis' estate, which has already turned over thousands of objects and documents to the John F. Kennedy Library in Boston.

Most of the buyers remained anonymous.

Some did not, including singer Jimmy Buffett, who bought over the phone a Jamie Wyeth lithograph of the president in a sailboat for $43,700.

Another was Marvin Shanken, the publisher of Cigar Aficionado magazine, who was the night's high bidder, purchasing JFK's humidor.

A high school student when he volunteered for Kennedy's 1960 presidential campaign, Shanken celebrated his purchase by lighting up in Sotheby's sale room.

``I, like many other people my age, was in love with the man and thought he was a great president,'' he explained.