After my boss rechecked the price,
1.Item number :A, when US $ exchange rate was : 6.5 in April, the price was $3.35/pc,
but now US $ exchange rate drops down to 6.3, and we will also add up the inner packing cost of $0.15/pc on top of it, then the best price is : $ 3.60/pc.
2. Item number :B,we only consider the cost of inner packing , and the best price is : $1.95/pc.
3. Item number :C,the price was $1.36/pc in Oct.,2010(order item:45000 ).
Considering at that time,US $ exchange rate was : 6.7, the final price then was : $1.45/pc.