For import/duty costs you could contact Narita Logistics and Services
http://www.phnom-penh.biz/cambodia-guide/phnom-penh/Service/moving_service_narita-logistics-and-services
When I inquired 2 years ago, brand new bikes attract duty of 49.5% based on invoice value + freight cost.
Customs have a database on new vehicle prices so you cant fake a low invoice value.
Customs duty on
used bikes is quite reasonable. It's 39.5% of the customs
book value based on year and engine size. For example, a 2007 model DRZ400S has a book value of $2000, so duty would total be ~$800.
Add another $400-$600 hundred for import permit, handling costs, and broker fees.
Some brokers will give you a lowball quote to win your business but then you get hit with higher costs once the bike arrives. Narita
seemed fairly upfront when I inquired.
As a foreigner, you can have a business 100% in your name, just cant own land.
You might find that using one of the local
connected bike importers is the way to go, rather than doing it yourself.