British YouTuber Simon Wilson flew from London to Oslo, Norway for just £3.99 ($A7.40) each way with Irish budget airline Ryanair.

“That is unbelievable. I can’t even get a taxi from my house to the corner shop for that price,” he said in a video of the flight uploaded to YouTube in April.

“That is the cheapest flight, not only that I am going to go on, but that I’ve ever heard.”

Wilson said he thought flights from London to Oslo would be up to £200 ($A370).

He discovered the cheap flights through a friend who travelled with him, fellow YouTuber

ClickForTaz.

She explained she found the prices by searching “Ryanair cheap flights”, which took her to a search page on Ryanair’s website that offered the airline’s cheapest prices on flights to destinations in Europe. The pair flew from London Stansted Airport, which offered the cheapest prices.

“I’ve used this trick and it works really well! Especially at Stansted Airport,” someone wrote in the comments.

Others said they had also found rock-bottom prices by googling “Cheapest Ryanair flights”.

Even more incredibly, Wilson found the food served on the flight was more expensive than the flight itself, such as a ham and cheese sandwich that cost €5.50 ($A8.95).

There were a couple of catches with the flight, however. The pair weren’t seated together even though they booked their fares together — although they ended up finding an empty row.

They also travelled with carry-on bags — they would have needed to pay to check in luggage.

Still, Wilson said the two-hour flight to Oslo was the cheapest flight he’d been on — prior to that, the least expensive flight he’d taken was Manchester to Dublin for $46 one way.

In the comments section, people explained they’d also had luck with ridiculously low-cost flights and said it typically happened when airlines needed to fill seats before the departure date.