Can I tell you, post 9-11 shipping out of the US(specifically air cargo) is a pain in the arse, due to the new regulations. As a result, the cost difference between boat and air is negligible but the time difference may not be.
If you can, drive the bike to Canada and ship with a freight forwarder there. Otherwise if you choose to ship by air, go with Hellmans, ShipMyBike.com, Motorcycle Express, or RoyalAirMaroc...
The "extra" money you may spend with a reputable freight forwarder will save you in the potential lost time of your trip. I lost one month because I went with Lynden initially and switched to RoyalAirMaroc halfway through. RAM can get it to London for you.