The cheapest ever EU flight I have had, was London to Madrid, and Barcelona to London, GBP75 return (was thinking it was A$ abut it can't have been). Madrid to Barcelona was GBP125 one way.

Last trip to EU, either Qantas or Lufthansa was tryng to charge A$1100 for Frankfurt to Oslo. After lots of comparisons got it down to a reasonable price, probably using crappy SAS (once was one of the best airlines) via Copehagen with an overnight stay from memory. That trip I did criss-cross Europe several times, Frankfurt to Naples, Naples to Brussels, Brussels to Lyon, Lyon to Frankfurt (or Brussels? or Copenhagen? - I forget), Copenhagen to Oslo. Stockholm to Helsinki, Helsinki to HK. HK to Sydney, Sydney to Adelaide! After setting off Adelaide to Singapore, had some fun with being arrested in Singapore !!! (never accidently lose a Nitro Express cartridge in your carry on bag when travelling in SE Asia

). Then to Frankfurt, Naples etc.