Hey,don't forget Ryanair is not all about low fares - they have some absolute whoppers in there too to balance out the revenue on flights.
Take tomorrow on Dublin to Cork - they are looking for Eur129.99 plus 20.94 in taxes and charges plus no doubt a few Euros for using your credit card and bringing some baggage - around Euro 160 for a flight of 25 minutes or so. Aer Arran, with flights before and after Ryanair (but only 3 /6 showing, so presumably the other 3 are full), are "cheaper" at Euro 84 and 63 plus taxes one way. Fact is they will all fill every seat because of the mid term and holidaty weekend, Cork Jazz Festival etc. but Ryanair know how to charge when the know they'll get it.
It's not just a "low fares airline", it's a business model which pushes big numbers of low fares and gets the cream with low numbers of high fares, making its money on the extras like card fees, baggage charges and, from next week, web check-in charges.