The basic fare includes a small cabin luggage, here's the Ryanair's policy. My quite large bagpack still qualifies, and I fit my laptop, spare shoes and enough clothes for a week in. Then you can get an extra cabin luggage for about €20, depending on the destination and/or a checked in luggage from about €25 or so.
Anyways, for most of our flights, we can easily go with the cheapest option, there's no need to carry extra stuff.