Gordon Robertson and I both imported ours. I brought mine over from England, I believe Gordon did the same thing. Currently I'm sitting in the Las Vegas airport (and am stuck here for 6 more hours!!!). I hired a freight company and an import agent to bring my Snow Trac into the US. The hardest part was the bloody paperwork, after I got the clearances, it was smooth and surprisingly fast. The biggest problems I encountered were finding people on the other side at a reasonable price, and coordinating the effort. I was very fortunate that the seller became a friend through the entire process and was very very accomodating of the delays and he took care of the transportation to the dock and even into the container.
Once at the dock, all the fluids need to be drained. (Oil and Gas). In my case, mine did not have a gas tank attached so it was simple to empty the gas. But the oil needs to be drained too, and then the Snow Trac needs to be pushed into the container and secured. Mine was secured at all four corners with stout rope. Cleats were nailed into the floor of the container and the ropes were attached to the cleats.
Prices I was quoted ranged from $2500 to $5500 complete with delivery to my warehouse/dock facility. Most shippers only want to bring the container to port in NYC and then you have to get it from the port via a trucking company.
The way to get it through customs is to hire a customs broker to clear it for you.