Man, I have never seen people complain this much. Yes, there's a cost to this, and if you're not comfortable putting in your high bid and avoiding the fee, just don't bid.
I can tell you, I was amazed at the fact there is no buyers premium. That alone puts these guys heads and shoulders above most auctioneers in terms of honesty. You should see how much buyers get taken to the cleaners in high-end comic book, coin, and car auctions. It's criminal. And the massive shilling that occurs in these auctions is insane also. I'm not going to tell my story (a friends actually) about another well known auction house and a pinball machine. (it was despicable). My gut is these guys are being more than fair, and just want to make sure they don't get taken to the cleaners or overwhelmed by casual bidders that are looking for steals. All you have to do is submit your high bid to avoid all fees. Nothing fairer than that.