My story wasn't with Ryanair, but I used to use Skyscanner to find the cheapest ticket, which is usually from a reseller agent instead of the airline (and whatever savings one made was wasted with time reading the 1-star reviews of how shit they are and then convincing oneself "Oh it'll be fine.").
One of these sites offered the ticket for dozens of Euros cheaper, and allowed me to go through the booking process until the end: I entered my CC, hit "Buy", and the next page was "Oops, the flight is no longer available at this price. The price now is: [the same price as booking with the airline]. Would you like to complete the purchase with this new price anyway?".
Fucking hell, it pissed me off so much that I said no and booked it with the airline after all.
One of these sites offered the ticket for dozens of Euros cheaper, and allowed me to go through the booking process until the end: I entered my CC, hit "Buy", and the next page was "Oops, the flight is no longer available at this price. The price now is: [the same price as booking with the airline]. Would you like to complete the purchase with this new price anyway?".
Fucking hell, it pissed me off so much that I said no and booked it with the airline after all.