It's true .. a ton of Africa Twin travel stories out there. One good one is from
long ago Hubber Maarten Munnik. He has a book:
100, 000 Miles Of Solitude: Maarten Munnik: 9781105408038: Amazon.com: Books
To save money, perhaps minimize transcontinental motorcycle shipping. For touring the EU, Russia, Mongolia and such ... you can do that from the UK, and the Africa Twin should be OK ... no shipping required.
For Australia, I'd buy a bike locally and re-sell once the Oz tour is done.
For the Americas, once again, I would not ship. Too expensive. Fly to California, buy a bike (no, no Africa Twins here but CHEAP!), do a big America's loop, sell off when back in USA or in S. America.)
Lots of good alternative bikes for two up that would do. The Suzuki V-Strom DL650 being a good choice, IMHO.
By going this route you could save THOUSANDS OF POUNDS in shipping costs. That translates to better living on the road and a longer trip.
For Asia and other areas, think about buying (buy back scheme?) or renting small bikes.
Good planning!