Ah, ha. another... I actually ordered a Zenza Bronica from Hong Kong in the 1960's. Price was about 1/3 that of the camera stateside. I do not remember any customs being charged at that time. However, some others have ordered equipment and what occurs is a customs broker becomes involved in some cases. They charge a fee, then assign a certain customs charge to the item. It is my understanding this is neither predictable nor consistent in spite of what the current custom rate may be on the item.
For me personally, I do not deal with unknown dealers, especially as the behavior may be inconsistent. Before ordering, Google the company name along with "reviews" and see what some folks are saying.
Overall, I have found I can save nothing anymore on these off shore deals. And absolutely no after sales support. In spite of some of the comments about the big dealers, I will go with the ones who are going to be there for me, such as B & H, Adorama, etc. the ones who help us keep the forum going. They are also the reliable ones.