I know that most people seem to have shipped their stuff over with a shipping company, but I just wanted to make a quick post for future reference for movers looking for other options.
I just sent 497lb of stuff in 17 boxes to the UK using UPS Expedited International. We paid for $6500 worth of insurance and the per pound rate turned out to be $2.97/lb. We dropped the boxes off on Friday at 4:30pm, and they were delivered our flat in Bristol this morning (the following Thursday).
We had a minor paperwork snafu because it appears that someone didn't think my C3 form or any of the associated paperwork (packing list, marriage cert, passport copy) were necessary and removed them from the plastic envelope they stick on the package. They decided that I only needed the UPS customs forms that I was forced to fill out when I dropped my packages off. It cost me $50 to fax new copies to UPS in the UK, but once they got them things cleared quickly and the packages were delivered on their originally scheduled date. I am going to call to try to get UPS to reimburse me the $50.
All in all, I am very impressed with the value for price. Since we didn't have enough stuff to fill a container or half container, and we couldn't do a port-to-port service, this turned out to be the cheapest option for us. We could have saved some money (about $0.84/lb) by going with surface mail through the Post Office. But we decided that the extra time it takes (6-8 weeks versus 3-5 business days) and the fact that you don't get any way to track your packages, made the extra cost from UPS palatable.
The only real complaint I have about UPS (other than the paperwork thing), is that they won't give you their price per pound. And the more you send in a single shipment, the lower your per pound price. But I found their online calculator to be quite accurate.