Lisa Marie decorated to Elvis's unique specifications at a cost of $600K and features a queen-size bed, gold bathroom fixtures and teak conference room

Neither 'museum piece' is fit to fly -- the Lisa Marie last flew on the day of Elvis's funeral

Two private jets once owned by Elvis Presley have appeared for sale on an aviation classified website amid their owner's ongoing feud with The King's estate.

Long a fixture at Elvis's Tennessee home, Graceland asked the owner of the Lisa Marie and smaller Hound Dog II in April to remove the jets by early 2015.

A furor soon erupted within circles of dedicated fans accustomed to seeing the jets at Graceland for 30 years.

Piece of history: Two private jets once owned by Elvis Presley have appeared for sale on an aviation classified website amid their owner's ongoing feud with The King's estate. Pictured is the larger of the planes, the Lisa Marie, a 1960 Convair 880

Hound Dog II: The Lisa Marie's smaller companion is also for sale. It served as a backup while renovations and additions were being made to the Lisa Marie

Now, for a 'serious offer,' one deep-pocketed superfan could call the 1960 Convair 880 and Lockheed Jetstar their own, according to sales site Controller.com.

Fans enjoy touring the planes for their direct connection to Presley and his jet-setting lifestyle, a sort of touchstone to the life of the King of Rock and Roll and his family.

By April of next year, the planes named Lisa Marie and Hound Dog II could be gone.

Elvis Presley Enterprises, which operates the Graceland tourist attraction, has written to the planes' owners saying they should prepare to remove the jets from Graceland by next spring.

Feud: The planes have appeared on an airplane classifieds site amid owner K.G. Coker's ongoing feud with the Graceland estate. Graceland announced in April that the planes would need to be moved, causing a fa uproar. Coker said that if forced to move the planes, he'd likely sell them off

Cilla responds: Graceland devotees were upset enough that Priscilla Presley was forced to respond

The planes have been a tourist attraction since the mid-1980s. They had been sold after Presley's death, and were eventually purchased by OKC Partnership in Memphis.

Seen here in 1955, Presley mainly used the Lisa Marie, which he had graciously appointed to his specs, using the Hound Dog II as a back-up jet

OKC Partnership and Graceland agreed to bring the two jets to Graceland.

The agreement called for OKC Partnership to receive a cut of ticket sales in return for keeping the planes there.

In an April 7 letter to OKC Partnership's K.G. Coker, Elvis Presley Enterprises CEO Jack Soden says the company is exercising its option to end the agreement and asks Coker 'to make arrangements for the removal of the airplanes and the restoration of the site on or shortly after April 26, 2015.'

When news of Graceland's wishes that the planes be removed broke, fan outcry was enough to force Priscilla Presley to respond.

'I see your posts about the planes,' Priscilla tweeted in early July. 'Please calm down, we're in the midst of negotiations. It's as simple as that. Thank you.'

In November, New York-based Authentic Brands Group bought Elvis Presley Enterprises and the licensing and merchandising rights for Presley's music and image from CORE Media Group.

As part of the deal, Joel Weinshanker, founder of the National Entertainment Collectibles Association, acquired the operating rights to Graceland, which attracts about 500,000 visitors each year.

After the sale, Authentic Brands said upgrades to the tourist attraction were planned. Earlier this year, Elvis Presley Enterprises announced plans to build a 450-room hotel, theater and restaurant, with a projected opening date of August 2015.

Flying limo: Named after Presley's daughter, the Lisa Marie is like a customized flying limousine, complete with a large bed, a stereo system, conference room and gold-plated bathroom fixtures. It was renovated after Presley bought it from Delta Air Lines. Presley took his first flight on it in November 1975

Fit for a King: Presley bought the Lisa Marie for $250,000 and according to its owner then put hundreds of thousands more into its renovations

Eye-catching: Lime and yellow seats are in Elvis' smaller plane, a Lockheed Jetstar named 'Hound Dog II'

Their plan was approved Tuesday by the Memphis City Council.

Today, Graceland visitors can buy a ticket that includes a tour of Presley's home-turned-museum and the two airplanes. Fans climb into the airplanes for an up-close look at their interiors.

The larger plane, a Convair 880 named after Presley's daughter Lisa Marie, is like a customized flying limousine, complete with a large bed, a stereo system, conference room and gold-plated bathroom fixtures.

It was renovated after Presley bought it from Delta Air Lines. Presley took his first flight on it in November 1975.

When Presley died on Aug. 16, 1977, Presley's pilot flew the Lisa Marie to California to pick up Presley's ex-wife, Priscilla Presley, to bring her back to Memphis.

The Lisa Marie's last real flight saw Priscilla Presley and actor George Hamilton flown from California to Memphis for Presley's funeral, after which it was returned to Memphis for good

Elvis's flying limo has dozens of custom speakers among top of the line other amenities for its day. It was designed by a team that had previously designed Air Force One

Bye ya'll: The beloved plane, long seen as a glimpse tourists could take inside the King's storied inner sanctum, may wind up somewhere other than Presely's Tennessee home next April

'Taking Care of Business': At one point, after the planes were sold following the singer's death, the Lisa Marie was owned by Raymond Zimmerman, owner of the Service Merchandise chain, according to Coker. The Hound Dog II was in the hands of Hustler head Larry Flynt for a time, Coker said

Sad end: When Presley died on Aug. 16, 1977, Presley's pilot flew the Lisa Marie to California to pick up Presley's ex-wife, Priscilla Presley, to bring her back to Memphis. They've not been moved since the 80s

The smaller jet, a JetStar named the Hound Dog II, was also used by Presley.

At one point, after the planes were sold following the singer's death, the Lisa Marie was owned by Raymond Zimmerman, owner of the Service Merchandise chain, according to Coker.

The Hound Dog II was in the hands of Hustler head Larry Flynt for a time, Coker said.