Who wants a pre-owned space shuttle? Everyone.

Condition: 27 years old, 150million miles traveled, somewhat dinged but well-maintained.

Price: $0.

Dealer preparation and destination charges: $28.8 million.

So, does anyone want to buy a used space shuttle?

Yes, it turns out. This old vehicle - the space shuttle Discovery - is an object of fervent desire for museums around the country, which would love to add it or one of its mates, Endeavour and Atlantis, to their collections.

Discovery is to return from orbit today, concluding its 39th flight and its space-faring career, but it will make at least one more ascent - piggyback on a 747 - to its resting place for public display. NASA will announce the final destinations for the three soon-to-be-retired shuttles on April 12, the 30th anniversary of the first space shuttle launching.

Some of the competing institutions have been campaigning energetically.

The visitors center at NASA's Johnson Space Center in Houston hired a marketing firm and set up a website, bringtheshuttlehome.com. Houston, the marketers argue, is the location of NASA's Mission Control, which guides the shuttles during flight.

The Intrepid Sea, Air and Space Museum in New York has collected more than 150,000 names on a petition urging that one of the shuttles be placed there.

The Museum of Flight in Seattle has perhaps gone the furthest: This week, it erected the first wall of a new $12 million wing to house the shuttle it may never get.

No one knows if these efforts, or dueling letters from members of Congress, are exerting any sway on the top decision-maker at NASA, Charles Bolden, who has said that he alone will decide where the shuttles end up.

NASA says 21 institutions have submitted proposals.

Other hopefuls include the Kennedy Space Center in Florida, the launching site of all of the shuttle missions; the California Science Center in Los Angeles; and the National Museum of the U.S. Air Force, near Dayton, Ohio, which got a boost from President Barack Obama's budget request for 2012 seeking $14 million to send a shuttle there.

After Discovery lands, only two shuttle flights remain. Endeavour is scheduled to launch in April, and Atlantis in June. Then the three will become museum pieces, with delivery expected next year.

There is also a fourth orbiter, the Enterprise, which was used for early glide tests but never went to space. The Smithsonian's National Air and Space Museum has the Enterprise on display at its Steven F. Udvar-Hazy Center near Washington-Dulles Airport.

Discovery will probably end up at the Air and Space Museum. NASA offered it there three years ago, but the Smithsonian has been reticent about whether it will accept.

After concerns that the Smithsonian could not afford $28.8 million, Congress, in a budget bill passed in December, included a clause that specifically excuses the Smithsonian from those costs. If NASA offered a shuttle to the Smithsonian, the bill decreed, it would be "at no or nominal cost."