traveling to and through Ireland

I think the concensus would be that flying by budget airline is the generally best way to get there. Once there, most choose to rent a car with bus being a close second. Trains are usually not effective.

Aer Lingus, although a traditional international airline, has to compete on price with cut-throat RyanAir to Britain, so comparison-shop. As ever, early purchasers get the lowest prices. The train system can be useful between cities, such as Dublin to Cork, but is not oriented to seeing the countryside villages.
http://www.irishrail.ie/home/

I'm with Paul. I've done the Irish ferries from Wales. It's a good experience - but it's not fastest or cheapest.