The problem with sea freight is the amount of time your box is left sitting around and, thus, vulnerable to getting squashed, mangled, dropped or otherwise lost or destroyed. All to save 50 bucks or so.
The British call that "penny-wise and pound-foolish".
Not completely accurate. It soes sit around for a bit true, but not in a box unless you pack it. Some Co.s ship fine antiques, sports cars etc. These are the shippers you need to work with. A complete bike is blanket wrapped and packed within the container, you recieve it at the port the same way. You can have the item photographed and insured before departure so that you have recourse it it gets scratched or dinged. The reallity is it is alot safer than shipping it boxed by Fed EX. I've had boxes stepped on, corners shredded etc. come off Fed EX and UPS trucks. It's not about saving a few $, it's about safe transport.
This link has a lot of info about continer and partial contianer shipping.
http://www.anglopacific.co.uk/