I generally use the buyee proxy bidding service which is linked to the Japan Yahoo Auctions site. If you find a part on Japan Yahoo Auctions that you want there will be a link for international buyers. Click the link and you then automatically bid through Buyee. They charge a bit of a premium but are reliable in my experience. Their postage set up is strange as well - if you buy multiple items, it is actually cheaper to have the items posted separately rather than in one package. They charge an extra fee for "package consolidation". Strange but true. You have to be careful purchasing certain parts as well. They won't, for instance post engine parts internationally so you can be caught out purchasing parts which they then refuse to mail. I did on one occasion manage to convince them to mail me an oil pump which I think was an exception to the rule. I've had no issues at all with various other parts such as carb parts, carb rebuild kits, master cylinder rebuild kits etc.