in 2008 I shipped my bike to Korea from Melbourne. I had the option of shipping to Vladivostok but the additional amount was just about equal to the cost of the ferry fare from Korea to Vladivostok and I could also not get direct flights to Vladivostok.
As MM has pointed out, cargo ships have not taken passengers for over 30 years so you will have to fly yourself anyway. It will take 4-6 weeks for your bike to ship to Korea and allow a further 1-2 weeks tor Vladivostok (no one ships direct from Australia /NZ to Vladivostok so any cargo has to change ships in Korea).
To give you an idea, I shipped Melbourne to Busan, flew to Vietnam (cheapest flight out of Australia), rented a bike in Vietnam, crossed to China, bought a bike and rode around for a month, sold it in Shanghai and flew to Busan, collected my bike then rode up the Korean Peninsula to Sokcho to catch the ferry to Vlad.
The opportunity to ride in Korea was well worth the small additional cost for temporary importation and insurance.
Enjoy your travels,
Garry from Oz - powered by Burgman