I looked into this when I was wanting to import some widgets. Since I was not doing partial container loads, importing by ship was actually a lot more than sending it regular carrier. The companies are called logistics companies. I would have needed a customs broker also, but I don't know if you need that to send out by ship. Plus it has to be left off and picked up at the ship. Maybe things have improved since then. This was about four years ago.
The fixed costs are too many and too high and its just not worth it for single item shipments. You mostly ship and get charged by cubic meters and that can get very pricey if your items are not too bulky. What I would suggest is to talk to a few local logistics companies. Any port city should have lots of them. There are too many little costs that probably will surprise you when you get the final bill. AND you must pay the final bill before they issue you the final BL..bill of lading. IF you dont have the BL, you wouldnt be able to release your cargo. Get a complete custom quote from them. Sometimes, if the customer inspect the cargo, you have to pay for that, both at the origin and destination ports. One of my customer once got away with both inspections and usually, most them do. The same customer got hit with both origin and destination inspections. PLUS, his cargo had to stay longer in the US customs house due to holidays etc. He had to pay quite a bit for the storage as well...something like 1500$. But his cargo was around 20 cubic meters.