Yamatoku has always done combined shipping for me and routinely gives me loyalty discounts - strange that your experience is so different. I will agree that some of his more sought-after-games auctions tend to get bidded up and sniped a lot but if you're picking up run of the mill stuff it's still a good deal.
Yeah, the combined shipping discount with Yamatoku is pretty good. But I don't even think about that until I've already won a single item at a good total price, and with shipping fees that are 7-9 bucks even with SAL for a single item, that can be tough. I've been using Yamatoku for over a decade, so I remember the days when I could get a N64 import shipped for 4 bucks. I can't really blame Yamatoku, of course, since the exchange rate has been terrible the last few years and I'm guessing shipping rates have gone up in Japan too, but Yamatoku used to have cheaper shipping than just about any other import seller on eBay (with a good combined rate on top of that) while now there are many other sellers with lower shipping rates. Add in the bidding typically going higher than with other sellers, and I'm now having to look elsewhere to find the best deals.