Here is my simple theory. There are two types of deals: friendly and unfriendly. Friendly deals happen between friends - people help each other, they have trust and comfort in negotiations, they enjoy making a deal and respect mutual interests. Unfriendly deals normally do not happen. They only happen when there are no friendly alternatives around. During unfriendly negotiations, seller is squeezed for all possible discounts, all terms are treated sceptically, fear and negativity are in the air, and with first chance deal will be off. Product has to be inevitably necessary for deal to happen in unfriendly environment.
It is natural that foreign companies and persons are treated friendly less often than local alternatives. But when product is good, and seller is right, then deals happen anyway. And deals help to make friends, and vice versa =)