The sign was put up as a joke by journalist Nicholas Whitehead and has been seen by thousands of people travelling eastwards along the A44 between Rhayader and Kington since 2002.
However, the road to Terminals 1 and 3 of the supposed airport leads only to a field on the outskirts of the village.
Having spent £25,000 to erect and maintain the sign, Nicholas has said that the joke is now on him and that it is too costly as he is now facing a bill of £1,500-a-year.
He now hopes that Facebook fans, known as the Frequent Flyers, will manage to raise £8,000 through crowd-funding so that the sign can be reinstated.
Nicholas, who used to edit the Radnor edition of the Brecon and Radnor Express and once wrote with Monty Python's Terry Jones, moved to live in Devon four years ago.
He said: "The sign came about after drinking local cider with friends one evening in Llandegley and I have never received a complaint about it.
"The bill-board was vacant and I asked Wrexham Signs Limited to put up the sin.
"Comments about it over the past 20 years have been universally good and it seems everyone loves it.
"Now it is established a lot of people feel it should remain but it was costing £1,500-a-year and is expensive for what it is.
"The plan is now for the Frequent Flyers to raise the money.
"There are as many as 2,700 fans on Facebook and they all get the joke.
"A crowd-funding campaign has begun to help get it much more cheaply and officially done.
"I am hoping that £8,000 could be raised within six months so that the Welsh Government and Powys County Council can authorise the erection of another sign and give permission for it to be installed.
"The sign has become an item of Welsh heritage.
"This way it would not cost them anything and it would prove to be value for money as it is not exactly a national monument but it is a national treasure."