I just sent my Goldwing to Frankfurt from Orlando using Stefan Knopf of
Knopf Tours. He also sends containers from California as well. The cost for me was about $1,400 US. I had to give him my title, registration (not necessary but I did), a power of attorney, and a doctors letter saying I am able to pilot a motorcycle (because I am over 65). I then had to buy 30 days of insurance (green card) for around $200 US. I also bought roadside assistance which isn't necessary but I thought advisable. I plan to be there for about a month beginning 5/21. The alternative to that was renting for about double the cost for a bike that I was not familiar with.
I looked into Air Canada, but their rates had not been published yet for summer. They were asking $3,100 at the time and while they said they usually have significantly reduced rates for summer, those rates were not going to be published until May. I could not wait that long.
There is another option if you are interested in going to Ireland. That is Martin (Wheatwacker) at
Motofeirmo. Buy a bike, ride it around, sell it back. That's what my buddy is doing. He just bought a Varadero (Honda) and will use it while we ride, then sell it back when he's done. No known cost at this point, because the sales price is unknown.
I can't really RECOMMEND either right now, because we are still in the process of making this happen. It's just a couple of alternatives to getting a bike in Europe.