Poland

I'm not sure anything will be cheap with the current oil prices. I usually start at Kayak.com and work from there. Set up fare alerts for possible itineraries. If you see a good deal, jump on it.

I go to Poland a couple of times a year on business, and have found that the first thing I do is look at Ryanair(ugh) or Airberlin(ahhh) and find what airports they fly from to Poland.
For instance, to get to Poznan, its US or flag carrier to Man, a taxi to the Liverpool airport to connect with a Ryan flight, or to Fra, or another DL airport to connect to AB to Krakow. Also, once in the EU, go to expedia.co.uk. and sometimes BA and others run specials inter EU. LOT is owned by Lufthansa and the fares into Poland are pretty steep using either unless you are going between October and April.

AMY my best deals on airfare have been with Lufthansa but i fly from Boston and usually to Warsaw or Cracow hope this helps