My experience has been a little different. I actually would not advice anyone to buy from an auction directly unless it is either a rare car, or a vehicle in extremely high demand hence unavailability in most exporters stocklists or finally, an expensive vehicle.
Next advice is as follows. only deal with an established company, with a large stocklist. Almost all companies require you to place a bidding fee, which is usually around usd 1,000 or jpy 100,000. The problem comes in the simple fact that once you pay the downpayment you are now bound to that company. Should a good deal appear in another company then you are pretty much screwed because you cannot take it. Bidding is stress. Every single day you have to comb though several auction houses and place bids. It may even take 4-5 months to get what you want. Factoring in the commission and inland transportation costs you may realize that you have not done much of savings. Placing the bid with an established company, say sbtjapan, is a plus, given that they tend to have a very large stocklist, and should you get one available from their stocklist, then you may still use the auction bidding downpayment as part of your payment. However let no company cheat you that they can refund your auction money. They will NEVER. The cash will be in your account and you will be asked to select a unit from their stocklist.
Finally, I have interacted with a referral (Nelson) given by matatuman on a different thread. The guy is a kenyan, very nice guy. He can still source given a downpayment and he personally verifies the cars condition and grade. Part of the problem is that the auctionsheets have comments written in japanese, and the vendors never interpret them. We are only forced to go with the overall auction sheet i.e. overall grading, interior and exterior grading and the auction diagram showing where the dents are, scratches, which panel has been replaced etc.