Normally, the online purchasing agent will indicate the price of a product as: $xxx plus $y freight charges
For the translation, it depends on what exactly you mean.
Can I just pay one count of the freight charges for the two pieces of products/goods I have bought?
-or-
As I will buy two items, can I just pay one count of the freight charges?
2012-04-20 12:35:02 補充:
First sentence: you want to clarify the total payment for two items.
Second sentence: you want to bargain to pay one less count of freigt charges.