A 16th Century castle is being put up for auction and could be snapped up by a new owner for just £55,000.
Any works to the building would need the consent of Cadw
The cost of developing Boverton Place, in Llantwit Major, Vale of Glamorgan, however, could be at least a six-figure sum, an architect has warned.
Overcoming planning restrictions because of the mansion's historical status, could also be difficult.
Interest in the auction of the property has been high and there are rumours a TV celebrity is among potential buyers.
Details of Boverton Castle and the 0.94 of an acre of grounds surrounding it, went up on the website of Herbert R Thomas on Saturday and has already attracted more than 2,400 hits.
Philip Thomas, who is handling the sale, said: "It's doing quite well. Normally we have about 4,000 hits per auction.
A small group of Shetland ponies currently graze in the castle grounds
"We've also had quite a few calls from all sorts of people. People who are interested in old buildings, interested in investments and those interested in sheltering money in land and property."
The same company arranged the auction of Llantwit Major Castle last April but it was called off at the eleventh hour after Welsh heritage agency Cadw called for more talks about its future.
Alan Gillard, principal architect of Gillard Associates in Llantwit Major, has already been contacted by several people wondering what kind of development would be possible at Boverton Place.
"It's a great opportunity for somebody," he said. "The trouble is, with planning laws as they are, it would be a severe problem for any development on that site.
"I suspect that's why it's at such a reasonable price - especially with almost an acre of land. The fact is that the castle building is a scheduled ancient monument and Grade II listed is very off-putting."
Developing the site would be extremely costly, he said, due to the expense of stabilising the structure and coming up with a high-quality, energy efficient design. Specialist building techniques would also have to be brought in.
Mr Gillard also joked that there were rumours that a celebrity with her own TV show already had her eye on the castle, being auctioned at a guide price of between £55,000 - £80,000
According to folklore, the castle is haunted by the Black Lady who was spotted by men working on the castle in the early 19th Century. She was described as a tall, shadowy figure dressed in mourning clothes.
Boverton Place was built around 1587 by Roger Seys, a land owner and attorney general of Wales. The family moved out in the late 17th Century and it fell into decay in the following century.
Vivian Kelly, from the Llantwit Major History Society, said: "The Seys line ended with a woman who married one of the Joneses from Fonmon Castle, so it went into their hands. They never lived there after that."
The ruins have survived to "considerable height" and are "visually impressive" said a Welsh Assembly Government spokesman.
He said: "In the case of ruinous buildings such as this, sustainable reuse, where feasible, can often present the best means by which its future can be secured.
"In principle, Cadw would have no objections to the potential reuse of such buildings but planning permission from the local authority would also be needed."