There is usually a "drop fee" when renting a car from one location and returning it to another however Ireland is an exception to that rule.
There is no additional charge to pick up a car at the Shannon Airport and returning to the downtown Dublin return. This makes it quite convenient to purchase airfare into one airport and fly home from the other, maximizing your time touring and enjoying the scenery, pubs and culture.
If you're looking for just a car rental, this is the place to get the lowest rates. Be sure to read the contract before committing!
A week at the airport can cost $100 or more but we've found a site that offers $1.00 - $2.00 off per day and you can compare pricing and location online.
With the Celtic Tiger roaring, roads are changing all over the place. GPS can be added to any car rental but nothing beats a good map -- for Ireland or anywhere in Europe.
Start your planning with a good travel book, even before asking for a price quote!