I google image your NOK BR3655g and saw it at motosport.com. In my experience, motosport.com is good, fast and ships using DHL. Check their website for availability

hm... real slow = 150km/h   

kalau slow = 200km/h

and normal = 299km/h

Spare parts are a tricky question. It all depends on the popularity of the bike. If you buying some rare breed like MV Agusta and so on, you must go back to principle and they can slaughter you.
General rule  is spare parts are cheaper overseas. So if you travel often or have eBay account, shop from there for all the spare parts. But consumables like engine oil, oil filter so on, just buy here.
Furthermore for our country, Japanese bikes are more popular and thus spare parts are no issue. If you have friends in Thailand, it helps a lot. Cheers.