Well, .01 EUR plus 'fees' (more fees than I've ever seen in my life - http://www.ryanair.com/en/terms-and-conditions#regulations-t...) including a minimum 6 EUR "Admin Fee" for the privilege of buying a ticket and a 40 EUR fee if you lose or don't print a boarding pass...
I didn't downvote you but I find it a little amusing that people in Europe can get worked up over an $8 ticketing fee on a $0.02 ticket. In the US, it can cost as much as $500 one-way to fly from Pittsburgh, PA to Philadelphia, PA. $79 one-way Chicago-Atlanta is considered so spectacularly cheap that the offer consumes most of the above-the-fold real estate on Southwest Airlines' website.
The fees are atrocious, but during promotions they sometimes sell tickets with taxes and fees included. I once bought a roundtrip Oslo-Edinburgh and the total charge was £1.98. The airport bus ended up being 20 times more expensive than the actual flight.
Can whoever downvoted me please explain yourself? You have to pay a 6 EUR "admin fee" to get the .01 EUR fare unless you use their proprietary approved prepaid product (which, amazingly, has its own fees! - The card alone costs 6 EUR plus an extra upcharge every time you put money on it@)
They often advertise flights for €0.01 but then charge ~€10 for various other things, so the actual price is usually about €15. However, it is possible to get a 1 cent flight, although it is rare.