Cheapo Transportation

The plane ticket over to Europe has to be one of the  most expensive things about my whole travel itinerary.  In 2012, I flew from Phoenix, AZ, USA to Dublin, Ireland  for around $804 USD in September. This year I will be flying from Phoenix, AZ, USA to Dublin, Ireland  for around $944 USD in June.  If I really looked hard enough I could find better deals but these are STILL going to look incredibly cheap next to the price of the same flight from websites like Expedia and Travelocity. 

What do I use?  Hipmunk You won't find cheaper airfare then on Hipmunk. I've compared Hipmunk to other airfare listers such as Expedia and Travelocity, Hipmunk has always been the cheapest.
How can I find the cheapest days to purchase my ticket?  Matrix Airfare Search It is what the travel agents use.   
Other important tips:  - Fly out midweek (cheaper than flying Friday when everyone else wants to) - Buy tickets on Tuesday (when new deals are released) - Allow your dates to be flexible (it could be $1200 on the 25th but $850 the 27th)

Cheap budget airlines: 

Ryanair (Europe)
Easyjet (Europe)
Allegiant Air (USA)  Have a cheap flight from Phoenix to Honolulu, Hawaii for around $300 round-trip (even next day)

Ryanair the Ikea of Airlines? Spain 2012

ALSO one of my favorite websites for traveling cheaply excluding flights is Seat 61 *Highly recommend*