We've done lots of touring in the past, including a 2 year ride, but have never had to pay a fee for flying with the bikes internationally.
It seems that airlines have now put an end to reasonable fees - United lists $200 one-way! My bike isn't even worth the $400 it would take to fly with it. (I thought it used to be $50 one-way.)
This summer, we rode US50 from Reno to Colorado, and just used FedEx to get the bikes there - about $35 one-way. Unfortunately, using FedEx or UPS overseas is closer to $250.
Any ideas on reasonable shipping methods for flying from the USA (Denver) to Western Europe (say, Frankfurt)?