>>>For sea-based shipping it is always suggested to use shipping agents. You can find shipping agents using just dial, they will take complete responsibility to deliver product to your doors. They will also take responsibility to clear it from customs.
See go with air cargo if stock is 2-3 cartons. Go with sea cargo is stock in large quantity more than 15 cartons. Initially when your stock is less then surely you will get less margin say 30-40% but then you increase volume then same product can fetch 60-70% margin and finally when you move from air cargo to sea-based shipping then it can easily cross 100%. I would recommend you to go with air cargo first.