My wife and I attended the IOM Centenary in 2007. I shipped my bike from Vancouver BC, Canada to Manchester, England on the same aircraft that we flew on. Cost was about $900 CDN each way. The IOM organizers had invited anyone with a Vincent to take part in a Parade Lap, closed roads, no speed limits.
We spent a week at the Isle of Man then three weeks touring England and Scotland.
The IOM lap was tremendous fun (234 corners?) but the icing on the cake was the 2500 miles of touring we did afterward.
I did consider renting a bike, but that would have meant missing out on the IOM lap plus it was cost prohibitive for a full month of use. As I recall the quote for a rental bike was something like £100 per day, so we were way ahead by shipping the Vincent over, plus it's nice to ride your own bike.
The arrangements for the IOM week were all done by the Vincent club. I do recall seeing the Steam Packet Co fees for the ferry ride- quite expensive, it's obvious they have a monopoly!
If you are able to do it, go for it.
It's been nine years now and I really want to get back there at least once more before entering the twilight help me home:-)
Here's a link to a Video Gerry Jenkinson made of the Vincent Lap. I made the closing credits, that's me in the gaudy red/black/white Suzuki leathers passing a Black Prince on my Rapide (engine 38, the 38 th Vincent built after WW2) The old bike was really flying that day.
Please let me know if there is a problem with the link.
https://m.youtube.com/?#/watch?v=b96qUn1EKsIGlen