Will Ryanair rip you off? I'll stand by the majority of the posters here. Yes.

We waited too long to book our Mystery Weekend trip and ended up on Ryanair (just missed a nice connection with LX to ZRH, but that's another story). To answer your "taxes" question:

Published RT Fare: €29.98
"Taxes, Fees, & Charges": €42.27
Aviation / WCHR Levy: €11.58

This does NOT include the €5 charge for booking with a credit card, and was done after deselecting anything like "priority boarding" (spending more time in that ad-filled-tube is not where I want to be) or baggage (only a weekend, it's okay). Sure, there are some fantastic deals to be had with FR (in fact, they're most often how I get to DUB and back) but that's when booked far in advance and when absolutely no other option exists.

Book the SK flight if it's still available. It's likely worth it. Or, if not, try something like Air Berlin. They're apparently fairly nice, much more so than FR from what I've heard.